A Truckee man is slated to begin serving federal prison time next month for possession of an unregistered .223-caliber machine gun and threatening to kill two U.S. Forest Service employees, one of whom was pregnant.

U.S. District Judge Edward Garcia sentenced Timothy C. Ryan, 47, to 20 months in prison last month for the federal charge of unlawful possession of the machine gun with an obliterated serial number, according to U.S. Forest Service officer Laura Clarke.

In addition to the federal conviction, Nevada County Superior Court Judge C. Anders Holmer sentenced Ryan last month to 180 days in jail for the state conviction of making death threats.

Ryan's federal and state sentences will be served concurrently in federal prison, and he is scheduled to begin serving his time Feb. 1, Clarke said.

Nevada County Sheriff's deputies and agents from the Bureau of Alcohol, Tobacco and Firearms arrested Ryan in October 2006 at his home on Greenlee Road.

About a month before the arrest, Ryan threatened to kill Clarke and a pregnant U.S. Forest Service fire investigator as they responded to an out-of-control burn pile on Ryan's property that was threatening federal land.

The women went to the house to cite Ryan for the fire.

"He said 'Get off my property,'" Clarke said. "He was yelling. I told him we just wanted to talk to him about the fire and to calm down. He said 'I'm going to kill you,' and 'Is this worth dying for?' "

As he made his threats, Ryan was walking toward a shed where officers found machine guns during the subsequent search warrant.

Investigators found three machine gun receivers and a Browning Model 1919 machine gun - in addition to the converted .223-caliber AR-15 assault rifle - inside several outbuildings, including a garage, Clarke said.

The assault rifle had been altered from a semi-automatic to a fully automatic machine gun. Several do-it-yourself books on building weapons also were found on Ryan's property, said Nevada County Sheriff's Capt. Ron Smith.

Any machine gun is illegal for a private citizen to possess, Smith added.

As part of the plea agreement, Ryan pleaded guilty to possession of one of the illegal guns, Clarke said.

The pregnant investigator has since delivered her son, who is "doing great," Clarke said. However, the woman wants to get out of law enforcement work because of the incident, Clarke added.

Ryan's sentence will be followed by 36 months of supervised release, Clarke said.