Hans Benjamin Singer - the 18-year-old son of deceased polygamist John Singer - appeared in federal court Friday on a felony charge of illegally possessing a pipe bomb.

The Utah Highway Patrol discovered the device in Singer's truck Oct. 13 after the truck crashed into a pole near Kamas."In the course of a routine inventory search, the bomb was found," assistant U.S. Attorney Mark Vincent said.

Members of Singer's family bombed an LDS church in Marion nearly three years ago and held law enforcement officials at bay for 10 days outside their farm. The standoff resulted in the shooting death of corrections officer Fred House. Benjamin Singer was 15 at the time.

U.S. Attorney Dee Benson said he does not know where Benjamin Singer was heading at the time of the accident or why he had the pipe bomb. Benson said the bomb was about 8 inches long but declined to give further details.

Singer pleaded not guilty to the charge of possession of an unregistered destructive device.

U.S. Magistrate Ronald Boyce ordered Singer incarcerated in the Community Treatment Center - a halfway house - until Monday, when Boyce will decide if Singer should be released on his own recognizance or jailed until the trial.

Singer was arrested in Summit County on Thursday and spent Thursday night in the Salt Lake County Jail, Benson said.

According to the Associated Press, agents from the Bureau of Alcohol, Tobacco and Firearm searched the Singer property Thursday for signs of other devices or evidence of manufacturing them, but did not find any, according to John Minichino, ATF agent in charge of the Salt Lake office.

Boyce delayed a decision on Singer's detention until Monday while the probation department researches Singer's Summit County contacts.

"The judge said he wanted to learn a little more about what kind of adult contacts he had in Summit County," Benson said.

Singer's mother, Vickie, brother John Timothy, brother-in-law Addam Swapp and Swapp's brother Jonathan are serving prison terms for their roles in the bombing of the church, House's slaying and the standoff.

If convicted on the bomb-possession charge, Benjamin Singer faces a maximum penalty of 10 years in prison and a $250,000 fine.