ANCHORAGE, Alaska (CNN) -- Republican vice presidential nominee Sarah Palin abused her power as Alaska's governor and violated state ethics law by trying to get her ex-brother-in-law fired from the state police, a state investigator's report concluded Friday.

Alaska Gov. Sarah Palin is under investigation for the firing of her public safety commissioner.

"Gov. Palin knowingly permitted a situation to continue where impermissible pressure was placed on several subordinates in order to advance a personal agenda," the report states.

Public Safety Commissioner Walt Monegan's refusal to fire State Trooper Mike Wooten from the state police force was "likely a contributing factor" to Monegan's July dismissal, but Palin had the authority as governor to fire him, the report by former Anchorage prosecutor Stephen Branchflower states.

However, it states that her efforts to get Wooten fired broke a state ethics law that bars public officials from pursuing personal interest through official action.

Monegan has said he was fired in July after refusing pressure to sack Wooten, who had gone through an acrimonious divorce and custody battle with Palin's sister. View a timeline of the investigation »

Palin and her husband, Todd, have consistently denied wrongdoing, describing Wooten as a "rogue trooper" who had threatened their family -- allegations Branchflower discounted.

"I conclude that such claims of fear were not bona fide and were offered to provide cover for the Palins' real motivation: to get Trooper Wooten fired for personal family reasons," Branchflower wrote.

The Branchflower report states Todd Palin used his wife's office and its resources to press for Wooten's removal, and the governor "failed to act" to stop it. But because Todd Palin is not a state employee, the report makes no finding regarding his conduct.