Two brothers accused of killing a U.S. Forest Service officer will go to trial May 9, a judge has ordered.

James and Joseph Pratt of Sandpoint each recited to Judge James Michaud "not guilty, your honor" 18 times when they were formally charged with 18 felonies, including first-degree murder.The 1st District Court trial at Sandpoint is expected to last four weeks.

Prosecutors have vowed to seek the death penalty for the brothers if they are convicted of killing Brent Jacobson, a Provo, Utah, native who is the only Forest Service law officer ever to die in the line of duty.

Jacobson, 41, was part of a posse tracking James Pratt, 29, and Joe Pratt, 27, after they allegedly terrorized eight people in a Sagle home Jan. 11.

After their alleged attempt to rob the home went sour, the brothers allegedly took a hostage for a short time and fired at a pursuing police officer, who was not hit.

They then allegedly led police through the northern Idaho woods on a manhunt that ended Jan. 12 shortly after Jacobson died in a gun battle with the suspects.

The Pratts received immunity from prosecution in 1982 for testifying against Christopher Boyce about Pacific Northwest banks they helped the escaped spy rob.