An investigation indicates the father-son duo suspected of killing a southwestern Montana sheriff's deputy first shot at the deputy as he pursued them and then turned around and fired more shots.

The information is included in court documents charging 61-year-old Lloyd Barrus with accountability to deliberate homicide in the May 16 death of Broadwater County Deputy Mason Moore. Barrus made an initial appearance on the charge via video on Friday. He did not enter a plea.

Barrus faces 14 counts of attempted deliberate homicide and two accountability charges in Missoula County for firing at officers during a pursuit after Moore's body was found near Three Forks.

Barrus' son, Marshall, died of injuries suffered in a shootout east of Missoula. His children told investigators their father and grandfather had been discussing a "suicide mission" against police.