In January 1985 a new employee started work at a fast-food restaurant in Sacramento. She was friendly with one of the young men on the staff, saw him several days a week and sometimes went out with him after work. Her name was Lisa Thomas, and she was a police officer from Belmont, a town on the San Francisco Peninsula. The man was Jon Scott Dunkle, and her department believed he had killed two boys.
Undercover work in a murder case is an act of patience and a gamble on human nature. It rests on the idea that a man who will say nothing to a detective across an interview table may say a great deal to a coworker, a stranger on a dark highway, a man in the next bunk or a friendly face on a hospital ward. The cases that follow run from wartime Berlin to a psychiatric ward in Kazakhstan. In some the deception broke the case. In others it produced a claim no court ever tested, a charge for something else entirely, or, in one Colorado case, a disaster that began with the government’s own informant.
John Davies was 15 when his father reported him missing in Belmont on November 8, 1981. Dunkle, then 21, was a close friend of the family; John’s mother had spent years helping him with his reading. Lance Turner, 12, also of Belmont, was killed on October 2, 1984. Belmont detectives questioned Dunkle repeatedly, with the FBI at their side by the end of 1984, and he denied everything, according to the California Supreme Court.
So the department sent Officer Thomas to his workplace. On February 9, 1985, the court recorded, he admitted to her that he had lied to investigators, while still insisting he had nothing to do with the deaths. On February 28, in a conversation that was recorded, she told him an invented story about a hit-and-run accident, and he answered with accounts of two assaults on other people in San Mateo County in 1982. Both people survived. ABC7 in San Francisco later reported that the officer had become his drinking companion and wore a wire, and that the operation ended with a burglary charge rather than a murder charge. By the autumn of 1986 he was in state prison on a burglary conviction. A second ruse that August, letters and a telephone call from an undercover narcotics officer using a false name and asking for money, drew no response at all.
The operation had not stopped him. On July 2, 1985, a 12-year-old Sacramento boy, Sean Dannehl, was killed. Dunkle later confessed to his death.
What finally broke the case was a different kind of undercover work. On September 16, 1986, Dunkle’s cellmate at the state prison in San Luis Obispo, Charles Rice, told a Department of Corrections investigator that Dunkle had talked to him about the killings. Rice then wore a wireless transmitter and recorded Dunkle describing the Davies and Turner deaths, and he told Dunkle that he had a friend in the FBI who would help him if he confessed. On October 3, 1986, Dunkle confessed to two FBI agents with Rice in the room. The California Supreme Court wrote that Rice asked for nothing in return; ABC7 reported that he had hoped for a deal on his own manslaughter charges.
Competency hearings consumed nearly three years. A San Mateo County jury eventually convicted Dunkle of the first-degree murders of John Davies and Lance Turner, with a multiple-murder special circumstance, and returned a verdict of death; the Dannehl killing was put before that jury at the penalty phase. The California Supreme Court affirmed the judgment on August 4, 2005. ABC7’s I-Team reported that his death sentence was on hold because a federal judge had ruled him incompetent to assist in his own appeal.
In 1987 and 1988 the deaths of several women in New Castle County, Delaware, south of Wilmington, came to light. In July 1988, the Delaware Supreme Court recorded, police started a decoy operation along a highway corridor there. Female officers posed as prostitutes and wore hidden microphones so that colleagues nearby could hear every word.
On the night of September 14, 1988, Officer Renee Lano, working as a decoy, radioed in the tag of a van that had passed her repeatedly; it came back to Steven Pennell, an electrician from Glasgow, Delaware, married, with two children. Her conversation with him was carried by her microphone to the officers listening. He asked whether she was a police officer, and she said she was not. In the course of the talk she drew from him personal details that matched an FBI profile of the man investigators were looking for, and fiber samples she collected that night were later tied to the case by laboratory analysts. WHYY, the public broadcaster for the region, interviewed her in 2014 under the name Renee Taschner; she remembered that his eyes had looked cold to her, with no life in them.
Pennell was placed under surveillance, and warrants followed. In November 1989 a jury convicted him of the first-degree murders of Shirley Ellis, 23, and Catherine DiMauro, 31; it could not agree on a third count, for Michelle Gordon, 22, and could not agree on death, so he received two life sentences. On December 18, 1991, the Delaware Supreme Court affirmed the convictions and upheld what the decoy officer had done. By then he had been indicted again, for the deaths of Gordon and of Kathleen Meyer, 26. Representing himself, he pleaded no contest to both on October 30, 1991, and the next day a judge sentenced him to death. He insisted to reporters that he was innocent and said he wanted to spare his wife and children further pain, United Press International reported. He was executed by lethal injection on March 14, 1992, the first execution in Delaware since 1946.
The oldest operation on the list ran in a city at war. When the blackout came to Berlin in September 1939, the S-Bahn trains east of Rummelsburg ran dark at night, and many of the women riding them alone were shift workers whose husbands were at the front. Between October 1940 and July 1941 eight women were killed and six more seriously injured in eastern Berlin, according to a 2026 account by t-online drawn from the files of the Berlin police history archive. Among the dead were Gerda Ditter, Elfriede Franke, Irmgard Freese, Johanna Voigt and Frida Korziol, 35, killed on the night of July 3, 1941, the last of the eight.
The archive’s records list the forces thrown at the case: the homicide squad, railway surveillance officers, a special unit of one commissioner and 20 men, 100 criminal investigators and 10 officers of the women’s criminal police. Male detectives dressed in women’s clothing rode the blacked-out trains as bait, t-online reports, and the local magazine Maulbeerblatt describes women officers used the same way. Detectives in railway uniforms worked on the line, and thousands of railway employees were screened: more than 5,000, in Maulbeerblatt’s count, and about 8,000 in Scott Andrew Selby’s, as Maclean’s summarized his book. At one point police spread a rumor that the hunt was being called off. The killings started again.
The regime fought the investigation as much as it helped it. Joseph Goebbels’s Propaganda Ministry ordered the press kept out, Maulbeerblatt reports, and the Maclean’s review says that detectives were forbidden to appeal to the public. The decisive lead, t-online writes, came from an undercover officer of the criminal police. Investigators went back over the night-shift lists, and a cleaner mentioned a switchman who had left his signal box during a shift. He was Paul Ogorzow, a Reichsbahn worker on the same line and a member of the Nazi Party.
He was arrested in the summer of 1941. He denied the accusations, then confessed; the historian Roger Moorhouse records that he admitted eight counts of murder and more than thirty counts of assault. A Berlin court sentenced him to death, and he was executed at Plötzensee prison the day after the sentence, on July 24, 1941, by Maulbeerblatt’s date.
Between September 1972 and February 1974, a series of killings and assaults on women in Cluj, in northwestern Romania, set off one of the largest militia investigations the city had known. The deaths investigators later attributed to one man included those of Cornelia Vaida in September 1972, Aurelia Ciule, 16, in December 1972, and Ilona Szilagyi, 84, in February 1974. The case was kept out of the press to avoid panic, Adevărul reported in 2017, and rumor in the city put the dead at about 200.
The militia mapped every incident and compiled more than a thousand files on people with psychiatric illnesses. One of them belonged to Romulus Vereș, a former locomotive driver retired on medical grounds. In February 1973, according to Adevărul, he had handed out written accusations against a woman neighbor he believed was entering his flat at night through the walls. Officers went to his home posing as doctors, and he talked to them about a plan to kill her. He was not arrested.
More than a year after the first death, a team arrived from Bucharest under Colonel Dumitru Ceacanica, head of the murder section of the militia’s General Inspectorate, as Gazeta de Cluj described him. He told the local officers they were looking for a mentally ill man, and had every witness statement taken again from the beginning. Then he and a young officer, Augustin Nona, went door to door through the blocks of flats, posing as officials of the county health department checking the register of psychiatric patients, Actual de Cluj reported in 2015. At one block a neighbor told them about the man on the fifth floor, newly moved in, who said he spoke with Satan. It was Vereș.
He was taken to a psychiatric hospital in February 1974. Psychiatrists diagnosed paraphrenia and concluded that he lacked discernment. The prosecutor, Iuliu Andrei, issued a decision not to begin criminal prosecution and recommended committal. Vereș did not confess, and he was never tried; he died in 1993 at the psychiatric hospital in Ștei, in Bihor County. Andrei told Actual de Cluj that he was not certain a modern court would have convicted him, but that the killings stopped once Vereș was taken away.
For years families and friends reported women missing from Vancouver’s Downtown Eastside, many of them Indigenous. On February 22, 2002, Robert William Pickton, a pig farmer from Port Coquitlam, was charged with two counts of first-degree murder. The next day RCMP officers questioned him in Surrey for about 11 hours. "Do I look like a murderer?" he asked them, the Associated Press reported.
The interview was not the only conversation that day. Police had placed an undercover RCMP officer in his cell, a man Pickton believed was another detainee, The Canadian Encyclopedia records. In that cell Pickton said he had murdered 49 women and had wanted to make it 50. The claim became the most quoted line of the case. It did not become a finding. At trial his defense argued that his taped statements came at the end of an exhausting interview or in leading conversations, and that a man of limited intelligence had been easily steered.
The Crown eventually charged him with the first-degree murders of 26 women and tried six of the counts first. On December 9, 2007, a jury in New Westminster acquitted him of first-degree murder and convicted him of the second-degree murders of Sereena Abotsway, Mona Wilson, Andrea Joesbury, Brenda Ann Wolfe, Georgina Faith Papin and Marnie Frey. Two days later Justice James Williams imposed life sentences with no parole for 25 years, the maximum. The Supreme Court of Canada affirmed the convictions on July 30, 2010, and the Crown stayed the other 20 counts on August 4, 2010, saying further convictions could not add to his sentence.
In 2012 the Missing Women Commission of Inquiry, led by Wally Oppal, condemned the police investigations as a blatant failure. Pickton died on May 31, 2024, after an assault by another inmate at Port-Cartier Institution in Quebec; that inmate pleaded guilty to first-degree murder in September 2025, Global News reported. The figure of 49 was never put to a jury as a count. It is a sentence spoken to a police officer pretending to be a prisoner, and it was never tested in court.
The Santa Monica police arrested Michael Gargiulo on June 6, 2008, on suspicion of the attempted murder of a woman in Santa Monica. Detectives in Los Angeles County had long suspected him in two earlier deaths: Ashley Ellerin, 22, a fashion student killed in the Hollywood Hills in February 2001, and Maria Bruno, 32, a mother of four killed in El Monte in December 2005. Back in Illinois, DNA had linked him in 2003 to the 1993 death of Tricia Pacaccio, 18, a neighbor in Glenview, but Cook County prosecutors had declined to charge him on that match alone.
After the arrest, undercover detectives spent 40 hours inside a jail cell with him, Courthouse News Service reported from the opening of his trial. Prosecutors played the jury audio from an El Monte jail cell in which, they said, he talked through an escape plan. That recording became the basis of an attempted escape count. It did not produce a confession. His lawyer, Daniel Nardoni, called the operation a subterfuge meant to draw an admission to the murders, and said Gargiulo never made one.
He was indicted for the Ellerin and Bruno murders on September 4, 2008, while still held on the Santa Monica case, but the trial did not open until May 2, 2019. On August 15, 2019, the jury convicted him of the first-degree murders of Ellerin and Bruno, with special circumstances of multiple murder and lying in wait, and of attempted murder and attempted escape. Jurors chose death in October 2019, and Judge Larry P. Fidler imposed the sentence on July 16, 2021. "Everywhere that Mr. Gargiulo went, death and destruction followed him," the judge said, according to the Associated Press. The automatic appeal to the California Supreme Court had produced no reported decision by October 2026.
Illinois charged him in 2011 with the first-degree murder of Tricia Pacaccio, and in September 2024 he was brought from California to face it. He denies all three killings. As of September 30, 2026, CBS Chicago reported, the Illinois case had no trial date.
Between 1985 and 2007, nine women and a 15-year-old girl were killed in South Los Angeles, and for more than two decades no one was charged. A Los Angeles police task force had DNA from the cases, but the profile matched no one in any database. In 2010 California tried something new: a familial search, which looks in the offender data bank for a close relative of an unknown suspect rather than the suspect himself. The state’s second such search in the case pointed to a man convicted the year before on an unrelated felony, and agents narrowed the field to his father. On June 30, 2010, they gave the LAPD a name, the California Attorney General’s office announced: Lonnie David Franklin Jr., a retired city sanitation worker.
A name was a lead, not proof, and detectives needed his DNA without alerting him. They placed him under 24-hour surveillance. On July 5, 2010, they followed him to a birthday party at a pizza restaurant in Buena Park, Vice reported. A detective posing as a busboy cleared his place and kept what he had used: napkins, glasses, a fork and a partly eaten slice of pizza. The laboratory matched the DNA to the profile from the killings. Franklin was arrested on July 7, 2010. "This arrest provides proof positive that familial DNA searches must be a part of law enforcement’s crime-fighting arsenal," Attorney General Jerry Brown said.
On May 5, 2016, a Los Angeles County jury convicted Franklin of ten counts of first-degree murder, with a multiple-murder special circumstance, and of one count of attempted murder in the case of a woman who survived in 1988. Judge Kathleen Kennedy sentenced him to death on August 10, 2016. He died at San Quentin State Prison on March 28, 2020, United Press International reported, with his automatic appeal still pending.
Some undercover work begins decades after a man has been locked away. Nikolai Dzhumagaliev, a firefighter from Uzynagash in Soviet Kazakhstan, was arrested in December 1980 after a series of killings of women in the Almaty region that began in January 1979. On December 3, 1981, a court ruled him insane and ordered compulsory treatment in a closed special psychiatric hospital, Informburo reported; no conviction for any of the killings has been reported. He escaped from psychiatric custody in 1989 and was recaptured in 1991, and since then he has been held at the Republican specialized psychiatric hospital in Aktas, outside Almaty.
In 2014 detectives in Aktobe, in western Kazakhstan, reopened the 1990 killing of a young female student who had come from a village to study in the city. Reviewing the old file, they were struck by its similarities to his earlier cases. That summer, according to Tengrinews and Zakon.kz, both citing the outlet Aktobe Times, an undercover officer was placed with him at the hospital, posing as a friend, and Dzhumagaliev described the killing to him. Police announced in September 2014 that the case raised the number of victims attributed to him to ten.
In 2014 the case was reopened, not tried; Tengrinews and Informburo reported in 2016 that he had been charged. No court has ruled on the Aktobe killing. As of August 9, 2026, NewTimes.kz reported, he was still under compulsory treatment at Aktas.
The Colorado case runs the usual logic backward. Scott Lee Kimball was a check forger with four felony convictions who had learned in jail that information was currency. In Alaska he told federal authorities that a cellmate was plotting to have a judge, a prosecutor and a witness killed, and the FBI used Kimball and an undercover agent to record the man, The Atavist Magazine reported in 2021. Westword wrote that the tip produced indictments but no convictions.
Moved to a federal prison in Colorado, he told an FBI agent from Denver, Carle Schlaff, that a new cellmate facing a drug case wanted witnesses killed. He was activated as a cooperating witness in September 2002, and the plan, according to The Atavist, was for him to pose as a hit man. On December 18, 2002, a federal magistrate released him on a $10,000 unsecured bond to work the case, 9News later reported from court documents. Prosecutors said in December 2003 that he had been paid $20,000; The Atavist puts the FBI’s payments at $50,000.
Over the next 21 months four people who knew him died: LeAnn Emry, 24; Jennifer Marcum, 25, the girlfriend of the man he was informing on; Kaysi McLeod, 19, the daughter of the woman he married; and his uncle, Terry Kimball, 60. The break came in 2006 from a check-fraud complaint. A Lafayette detective, Gary Thatcher, called the FBI on March 8, 2006, and learned that his suspect was one of the Bureau’s own informants. Schlaff told him he might have "a serial killer on your hands," The Atavist reported.
On October 8, 2009, in Boulder County District Court, Kimball pleaded guilty to two counts of second-degree murder and admitted responsibility for all four deaths. He was sentenced to 70 years. In 2012 the FBI’s Office of Professional Responsibility faulted Schlaff’s handling of him and suspended him without pay, The Atavist reported. The case turned once more in 2017, when a former cellmate of Kimball’s at the Sterling Correctional Facility went to a federal agent, became a confidential source for the FBI, and helped expose a plan to break Kimball out of prison. In January 2020 Kimball pleaded guilty to attempted escape and received four more years; solicitation charges were dropped, CBS Colorado reported. The Federal Bureau of Prisons listed him at USP Coleman II, in Florida, as of October 22, 2026.
Not every sting is aimed at a killer. Some simply sweep him up. In May 1982 Gary Ridgway, a truck painter in King County, Washington, was arrested after soliciting prostitution from an undercover officer, the Associated Press reported at the time of his murder arrest. On July 15, 1982, the first of the deaths that gave the Green River case its name came to light in King County, HistoryLink records. On November 16, 2001, he was charged again, with loitering for the purpose of soliciting prostitution, and he pleaded guilty, Sheriff Dave Reichert said.
Two weeks after that, on November 30, 2001, he was arrested and charged with four counts of aggravated murder. On November 5, 2003, he pleaded guilty to 48 counts of aggravated first-degree murder, HistoryLink recorded. He was charged with a 49th killing in February 2011 and pleaded guilty to that count as well, KOMO News and the Kent Reporter reported. The two vice arrests bracket the whole series: the system had him in hand on a minor charge at the start and again at the very end.
The operations that worked best were the simplest. A decoy in Delaware listened carefully and brought back a few fibers. A detective in a busboy’s apron cleared a table. A colonel from Bucharest and a young local officer carried a cover story from door to door. Each produced evidence or a name that could stand on its own once the deception was over.
The cell conversations are harder to weigh. The officer in Pickton’s cell came away with a number that has followed the case ever since, and no jury ever convicted on it. Forty hours in a cell with Gargiulo yielded an escape count and no admission. The undercover friend at Aktas produced a police attribution and nothing that has reached a courtroom. Even in Belmont, months of patient work by a police officer posing as a coworker did not stop the killing of a third boy; the confession came only when a prisoner with his own motives wore a transmitter.
And Kimball is the warning at the edge of the subject. Undercover work depends on people who can lie convincingly, and the FBI chose to trust a career con man with four felony convictions. Four people he knew died while he was working for the government.
• October 1940 to July 1941: eight women are killed in eastern Berlin; male and female officers ride the blacked-out S-Bahn as decoys.
• Summer 1941: Paul Ogorzow is arrested after a lead from an undercover criminal police officer; he is executed at Plötzensee, July 24, 1941 (Maulbeerblatt’s date).
• September 1972 to February 1974: killings and assaults on women in Cluj, Romania.
• February 1973: officers posing as doctors visit Romulus Vereș at home; he is not arrested.
• February 1974: investigators posing as health officials identify Vereș; he is taken to a psychiatric hospital and is never tried.
• December 1980: Nikolai Dzhumagaliev is arrested in Kazakhstan; a court rules him insane on December 3, 1981.
• November 1981 and October 1984: John Davies, 15, and Lance Turner, 12, are killed in San Mateo County, California.
• May 1982: Gary Ridgway is arrested after soliciting an undercover officer in King County, Washington.
• January to February 1985: a Belmont police officer works undercover at Jon Scott Dunkle’s Sacramento workplace and records him on February 28.
• July 2, 1985: Sean Dannehl, 12, is killed in Sacramento.
• October 3, 1986: after his cellmate records him, Dunkle confesses to FBI agents.
• July 1988: Delaware police begin a decoy operation in New Castle County.
• September 14, 1988: decoy officer Renee Lano talks with Steven Pennell at his van.
• November 1989: Pennell is convicted of two murders; Dunkle’s murder trial opens in October 1989.
• March 14, 1992: Pennell is executed in Delaware.
• November 16, 2001: Ridgway is charged in a prostitution sting; he is arrested for murder on November 30.
• February 22 and 23, 2002: Robert Pickton is charged with murder and speaks to an undercover officer in his cell.
• December 18, 2002: Scott Lee Kimball is released to work as an FBI informant.
• November 5, 2003: Ridgway pleads guilty to 48 murders.
• August 4, 2005: the California Supreme Court affirms Dunkle’s death judgment.
• June 6, 2008: Michael Gargiulo is arrested in Santa Monica; undercover detectives spend 40 hours in a cell with him.
• October 8, 2009: Kimball pleads guilty to two counts of second-degree murder.
• July 5 and 7, 2010: a detective posing as a busboy collects Lonnie Franklin’s DNA; Franklin is arrested two days later.
• July 30, 2010: the Supreme Court of Canada affirms Pickton’s six convictions.
• Summer and September 2014: an undercover officer at the Aktas hospital hears Dzhumagaliev describe the 1990 Aktobe killing; police announce the attribution.
• May 5, 2016: Franklin is convicted of ten murders.
• August 15, 2019: Gargiulo is convicted of two murders, attempted murder and attempted escape; he is sentenced to death on July 16, 2021.
• January 2020: Kimball pleads guilty to attempted escape after an FBI source exposes the plan.
• March 28, 2020: Franklin dies on death row with his appeal pending.
• May 31, 2024: Pickton dies after an assault by another inmate.
• September 30, 2026: Gargiulo’s Illinois case has no trial date.