The stepson of notorious child killer Ward Weaver has been sentenced to life in prison for his role in the killing of a marijuana dealer two years ago.

Francis Weaver was sentenced Friday in Oregon City, a couple days after he was convicted of murder, robbery and being a felon in possession of a firearm. Police said Weaver provided the gun that was used to shoot Edward Spangler of Grants Pass in the robbery-turned-homicide.

"I know he was a good man, a very good man, and a good son," Weaver tearfully told the victim's family. "That was never supposed to happen."

The killing extends the history of Weaver murders to a third generation.

Weaver's stepfather, Ward Weaver III, was convicted of aggravated murder in 2004, two years after the bodies of Ashley Pond and Miranda Gaddis were found in his backyard. Before the discovery, the search for the 12-year-old Pond and 13-year-old Gaddis riveted Oregon for months and landed the missing girls on the cover of People magazine.

The case broke when Francis Weaver, then 19, called emergency dispatchers to report that his girlfriend accused Ward Weaver of raping her, and his father had privately admitted to killing Pond and Gattis.

DNA tests from the Pond/Gattis case revealed that Francis Weaver is not Ward Weaver's biological son, though both men had previously believed he was. Francis Weaver's mother, Maria Shaw, told The Associated Press in 2014 that Francis's father was either a now-deceased Marine named Richard or a Navy man named Christopher.

Ward Weaver III is serving a life sentence with no chance for parole.

Francis Weaver's step-grandfather, Ward Weaver Jr., sits on California's death row. In the 1980s, he was convicted of killing a man whose car had broken down and of kidnapping, raping and murdering the man's girlfriend. Her body was found buried beneath a deck at his home in Oroville, California.

Francis Weaver was one of four people convicted in the 2014 case. The man who police say pulled the trigger, Michael Orren, has pleaded guilty to aggravated murder, and he will be sentenced next month. Two others were convicted of robbery and sentenced to more than seven years in prison.