A Fargo truck driver jailed in that city on a weapons charge is now accused of shooting to death a couple on their Wells County farm.

Aron Nichols, 28, faces two counts of Class AA felony murder in the deaths of Donald Willey, 70, and his wife, Alice, 67, State's Attorney Kathleen Trosen said Saturday. Nichols faces up to life in prison without parole if convicted. A date for a bond hearing was not immediately set.

The couple's bodies were found April 7 when firefighters were called to their burning rural home near Sykeston about 6 a.m. Authorities said the home was destroyed.

Authorities declined to comment Saturday on a possible motive for the killings, but Trosen said Nichols has a connection with the Willeys - his fiancee's daughter is the Willeys' grandchild.

Trosen said the child is the daughter of Andrew Willey, Donald and Alice's son who was killed in a helicopter crash in 2002 while he was working as a paramedic in Aberdeen, S.D., and Tamara Sorenson, who was his girlfriend and is now Nichols' fiancee.

Trosen, citing the ongoing investigation, would not say if Sorenson also was a suspect. She did say that Sorenson had not been arrested. She declined to say where the grandchild was.

Nichols was served with a warrant early Saturday afternoon at the Cass County jail in Fargo, where he was being held on a felony charge of possessing a short-barrel shotgun. He had been arrested on Thursday after a search of the residence in Fargo that he shares with Sorenson, Trosen said.

Nichols is to have a preliminary hearing on the weapons charge in mid-May, Trosen said. His bail on that charge is set at $25,000 cash.

The prosecutor would not comment on what led to Thursday's search but said Nichols at the time "was considered somebody that could be a potential suspect." She would not say why authorities waited two days to charge him with killing the Willeys.

The autopsy on the Willeys determined that they died of gunshot wounds, before the fire happened, Trosen said. She would not say whether authorities believe the shotgun was the murder weapon.

Alice Willey had head and chest wounds, and the chest wound resulted from a shot that entered her back, Trosen said. Donald Willey is believed to have been shot behind the left shoulder, she said, though that finding is preliminary.

"The medical examiner indicated that neither one of them could have self-inflicted their wounds," Trosen said.

She declined to say how the bodies were found, or whether anything was taken from the home.

The cause of the fire still had not been determined Saturday, though Trosen said the blaze is considered suspicious.

The Willeys were known for their volunteer work in Sykeston and Carrington, and they were emergency medical workers for 20 years. Donald Willey was a retired volunteer firefighter.

The Willeys also started the Carrington chapter of a support group called The Compassionate Friends after the death of Andrew Willey.

The last murder in Wells County, which has about 5,000 people, was in the 1970s.