Three teens charged with trying to kidnap a Roanoke County woman and hold her for ransom filed court documents Friday indicating they will plead guilty.

The fourth and final defendant in the case filed a similar plea agreement Thursday.

"We're just glad to bring closure for the victims," Assistant U.S. Attorney Charlene Day said.

From the start, the case against Mohammed Hussein Guhad, 19; Joshua Kasongo, 19; and Anthony Eugene Boyd-Muse, 18, all of Roanoke, and Luke Musa Elbino, 19, of Vinton was an unusual one.

All four were charged with conspiracy to kidnap and attempted kidnapping after trying to abduct Audrey Levicki, federal investigators said. Authorities said the teens selected her as a target because her husband is George Levicki, the CEO of Delta Dental insurance, and they thought he could afford a large ransom. It was the first kidnapping case in U.S. District Court in Roanoke in years, several court officials said.

Another peculiar feature of the case was that Guhad, Elbino and Kasongo are children of refugee families -- Guhad is from Somalia and Elbino from Sudan, and Kasongo is a citizen of Congo whose family came to Roanoke after fleeing genocide in Rwanda. All are in the country legally.

At detention hearings early in the case, U.S. Magistrate Judge Michael Urbanski commented on the irony of the defendants' families seeking refuge from terrorism, only to have their children charged with kidnapping.

All four teens are pleading guilty to conspiring to kidnap, a charge that carries a maximum sentence of life in prison, though federal sentencing guidelines probably will call for a shorter term.

According to accounts Day presented at their detention hearings, Kasongo, Elbino and Guhad came up with the kidnapping plan, then approached Boyd-Muse, who attended Patrick Henry High School with Guhad. Boyd-Muse, the only U.S. citizen among the defendants, agreed to let them use a camper behind his home as a prison for their captive in exchange for a promised $30,000, Day said.

Boyd-Muse also gave Guhad a handgun that was damaged and that investigators said may or may not have been able to fire, Day said. Guhad did not take the gun when he went to the Levickis' home on the afternoon of April 6.

Instead, Guhad was carrying a backpack containing duct tape and a pillow case, and Elbino had a BB pistol that looked like a real gun. They told Audrey Levicki they were conducting a survey for the Red Cross, according to investigators.

When she would not open the door completely, Elbino tried to reach inside. Levicki slammed the door on his hand, and the pair ran back to the car, where Kasongo waited.

They drove away, but a neighbor followed until police stopped them.

Day said formal plea hearings probably will be scheduled for next month, with sentencing to follow later.