A divided federal appeals court yesterday reinstated a state manslaughter charge against the FBI sharpshooter who killed the wife of white separatist Randy Weaver and held that the marksman was not automatically entitled to immunity from prosecution.

In a 6 to 5 decision, the court raised sharp questions about the testimony of FBI sniper Lon Horiuchi about the bloody 1992 siege of Ruby Ridge in northern Idaho and said at one point that his actions seemed "more akin to recklessness than reasonable conduct."

"Assuming the facts alleged by the state," U.S. Circuit Judge Alex Kozinski wrote in the majority opinion, "this is not a case where a law enforcement officer fired his weapon under a mistaken belief that his fellow agents or members of the public were in immediate danger.

"Rather, a group of FBI agents formulated rules of engagement that permitted their colleagues to hide in the bushes and gun down men who posed no immediate threat. Such wartime rules are patently unconstitutional for a police action."

A federal judge in Boise had ruled in 1998 that Horiuchi was immune from prosecution under Idaho law because he was "acting within the scope of his federal authority" when he fired a bullet through a glass pane of the Weaver cabin door, killing Vicki Weaver and injuring family friend Kevin Harris.

Yesterday's decision by the U.S. Court of Appeals for the Ninth Circuit, meeting in San Francisco, said the finding was premature and sent the case back to U.S. District Judge Edward J. Lodge for evidentiary hearings to determine whether Horiuchi should stand trial.

"This is a good day for the citizens of the United States," Weaver, now living in Iowa, said of the ruling. "Someone has to hold these people accountable. It would be a scary country if they weren't. It's scary enough as it is."

FBI Director Louis J. Freeh said "we are very disappointed . . . and will continue to support Agent Horiuchi and his family as this litigation continues."

Idaho prosecutors, who have accused Horiuchi of involuntary manslaughter under state law, said they would proceed with the prosecution as soon as the papers reach Lodge. Special state prosecutor Stephen Yagman said he would pursue it "zealously."

The five dissenting judges said what happened at Ruby Ridge was deplorable and that Horiuchi "probably made serious mistakes in judgment." But they accused the majority of inventing disputes that had not been raised before and improperly relying on Senate testimony instead of sticking to the court record.

"There will be times when [federal] agents make mistakes, sudden judgment calls that turn out to be horribly wrong," the dissenters said. "We seriously delude ourselves if we think we serve the cause of liberty by throwing shackles on those agents and hauling them to the dock of a state criminal court when they make such mistakes, especially when the prosecuting state concedes they acted without malice."

One of the federal government's worst law enforcement debacles, the siege began in August 1992 when three federal marshals, part of a surveillance operation that had been spying on Weaver for more than a year, encountered Weaver, his 14-year-old son Sammy and Harris on a logging trail near the Weaver family cabin. The ensuing gunfight left one of the marshals, William Degan, and Sammy Weaver dead.

Horiuchi and fellow FBI sharpshooters were among hundreds of lawmen who surrounded the cabin the next day. When Weaver, Harris and Weaver's daughter Sara emerged, Horiuchi fired a first shot at Weaver, saying that he thought Weaver was pointing a weapon at an FBI helicopter flying overhead.

When the three fled for the cabin, with Vicki Weaver holding the door open with a baby in the other arm, Horiuchi fired again, saying he was trying to kill Harris -- whom he had mistaken for Weaver -- and that he "did not see Vicki Weaver behind the door."

Voicing strong doubts about Horiuchi's testimony, the majority said the FBI sharpshooter admitted at one point that he thought someone else might be standing behind the door and might even have seen Vicki Weaver when she came out on the porch after the first shot. Kozinski was also skeptical of Horiuchi's claims that he thought the helicopter was in danger and suggested he may have made up that story "to cover up his real reason for the shooting, which was to follow the orders he had been given to shoot any armed man on sight."