Casey Lowell Hickok, 32, of Copeland, Fla., was arrested for allegedly murdering his father. Collier County Sheriff's Office photo.

A Florida fisherman was sentenced Monday to nearly a decade in prison for fatally beating his father on their fishing boat.

Casey Hickok, 32, of Copeland, Fla., hit his sleeping father Robert Hickok, 54, with a spare engine alternator on the boat No Bitchin’ March 18. In court the younger Hickok said he struck his father after the older man sexually molested him.

The vessel was 66 miles off Marco Island that day when captain Yamer Jesus Perez called the Coast Guard for help, according to the original criminal complaint by federal prosecutors. A Coast Guard rescue swimmer boarded the boat and found Robert Hickok dead with head and facial injuries, and the boat was escorted to Fort Myers Beach.

Perez told Coast Guard investigators he was repairing the boat’s alternator, using parts from a spare, when Casey Hickok offered to help. Hickok then picked up the second alternator, walked to where his father was sleeping, and struck him twice, Perez told investigators.

A grand jury indicted Hickok on March 27 on the charge of killing his father with “malice aforethought” and he faced sentencing for second-degree murder. But after a controversial decision by the Lee County medical examiner’s office to change its autopsy report in the case, Hickok made a June 17 plea deal to a lesser assault charge.

The change in in the report listed the cause of death as undetermined instead of homicide and made the plea deal possible, defense attorney Lee Hollander told the Naples Daily News.

In court testimony Casey Hickok said he and his brothers were abused for years by their father. U.S. District Court Judge Thomas Barber agreed that Hickok had long experienced abuse, and said his cooperation in the plea deal merited a reduced sentence. But in sentencing Hickok to 115 months he also cited Hickok’s previous criminal history of lesser assaults and said he would pose a danger to others out of prison.

In addition to prison time Hickok must participate in mental health and substance abuse treatment, and submit to probation and 100 hours of community service after release.