FAIRBANKS - New charges in the killing of two Alaska State Troopers in Tanana allege that the shooter and his father "manipulated" or "repositioned" the slain troopers' pistols.

Additional charges handed up in a supplemental indictment Friday now charge Nathanial Kangas, 20, and his father, Arvin Kangas, 58, with evidence tampering and hindering prosecution for reaching under the slain troopers' bodies to move the weapons.

According to an account of the May 1 shooting given by trooper director Col. James Cockrell at a news conference the following day, neither trooper had a chance to draw his weapon before they were gunned down.

Nathanial Kangas was previously charged with two counts of first-degree murder as well as additional charges second-degree murder, assault and a single count of evidence tampering. The new indictment adds three evidence tampering charges.

Arvin Kangas was previously charged with one count of evidence tampering and one count of hindering prosecution. The new indictment adds three evidence tampering and three hindering prosecution charges.

Both men have pleaded not guilty to the original and the new charges.

Nathanial Kangas is accused of firing a rifle seven times at Sgt. Scott Johnson and Trooper Gabe Rich, killing them both as they tried to arrest his father. The two troopers had traveled to Tanana to arrest Arvin Kangas for an incident against a village public safety officer. Arvin Kangas was charged with misdemeanor assault for that incident.

Nathanial Kangas was arrested "shortly after" the two troopers were killed. Arvin Kangas fled to another residence and surrendered to a trooper special emergency response team more than seven hours later, according to the troopers' narrative.

The new charges also accuse the two Kangas men of moving marijuana plants and seeds out of the house following the shooting.

Both Kangas men pleaded not guilty to the additional charges at an arraignment Monday afternoon.

Contact staff writer Sam Friedman at 459-7545. Follow him on Twitter: @FDNMcrime.