Daniel Greatwalker Jr., 23, is accused of killing Perry Picotte by striking and stabbing him.

A North Dakota man whose father is serving life in prison for one of the grisliest killings in state history is charged with first-degree murder in a case unsealed Friday in federal court.

Daniel Greatwalker Sr., of Belcourt, was convicted in November 2002 of killing 43-year-old Linus Wallette, whose body was found in a wooded area on the Turtle Mountain Indian Reservation. Authorities said Wallette was beaten with a pickax, knife and hammer.

Daniel Greatwalker Jr., 23, is accused of killing Perry Picotte by striking and stabbing him. Picotte, 21, was reported missing on Nov. 27. His body was discovered on Dec. 2.

Greatwalker made his first appearance Thursday. He's scheduled to be arraigned Tuesday in Bismarck.

U.S. Attorney Timothy Purdon, asked to comment on the nearly four-month delay in charges in the case, said it was an "active ongoing investigation" led by the Bureau of Indian Affairs and involving the FBI.

"In many cases investigators need to rely on members of the public who have information being willing to come forward, and sometimes that takes time," he said.

Purdon would not talk about specifics of the case. The younger Greatwalker is being represented by the federal public defender's office for North Dakota. The head of that office was not immediately available for comment.

Greatwalker is also charged with covering up evidence, including a knife or knives, clothing and shoes.

Investigators say that Daniel Greatwalker Sr. attacked Wallette during a night of drinking and using drugs in April 2000, as revenge for the 1997 killing of his father, Clarence, by a member of the Wallette family.

Several witnesses saw Greatwalker beating the victim, wielding the bloody murder weapons and wearing blood-soaked clothing, court documents show. Greatwalker, who was 32 at the time, allegedly showed several people Wallette's body and asked for help getting rid of it.

Both Assistant U.S. Attorney Dave Peterson and U.S. District Judge Patrick Conmy warned jurors at the start of the seven-day trial about the gruesome evidence in the case.

"''This is not going to be a pleasant experience," Peterson said.