A key prosecution witness says he agreed to help a Pennsylvania man kill a pharmacist and the pharmacist's girlfriend as part of a robbery plot.

Paul Weakley took the stand Tuesday in Hugo Selenski's homicide trial. He told a jury he agreed to help Selenski kill Michael Kerkowski and Tammy Fassett and bury their bodies in Selenski's yard.

Prosecutors say the pair robbed Kerkowski of tens of thousands of dollars he'd made from illegal drug sales. Weakley says Selenski needed the money to help his girlfriend cover a check she wrote to buy a house.

Weakley avoided a potential death sentence by pleading guilty to federal charges in connection with the case.

The defense says Weakley is the sole culprit.

Authorities found at least five sets of human remains on Selenski's property near Wilkes-Barre, Pennsylvania.