This is a family annihilation carried out by two people in one night, not a series, and it is in the archive under that qualification. It is here because Michele Anderson is, and the two cases cannot be read apart.
Joseph Thomas McEnroe was living with Anderson in a mobile home on her parents' property at Carnation, in King County, Washington. There was a long-running argument about rent and about money Anderson said her brother owed her. The sum at the centre of it was a few hundred dollars.
On December 24, 2007 the two of them shot dead six members of her family. Her father Wayne, sixty, and her mother Judith, sixty-one, were killed first. The rest arrived later for Christmas Eve dinner and were killed as they came into the house: her brother Scott and his wife Erica, both thirty-two, and their children Olivia, five, and Nathan, three. The bodies were moved and concealed on the property. A .357 Magnum was used.
Both were arrested within days.
The two were tried separately, and his trial came first. In March 2015 a King County jury convicted him of six counts of aggravated first-degree murder. The same jury declined to impose the death penalty, and he was sentenced to life imprisonment without the possibility of parole. Anderson was convicted in March 2016 and received the same sentence.
Washington's death penalty was struck down by the state supreme court in 2018 and abolished in 2023, so neither of the sentences the prosecution originally sought could be imposed today.
The victim count of six is the same for both of them, because they were convicted of the same six killings. It is one event counted once, not twelve deaths.