ROCKLAND, Maine — A Rockland man remains in jail for what Knox County Sheriff Donna Dennison called “one of the worst” domestic violence cases she has seen.

Douglas Merrifield, 33, was arrested Wednesday afternoon in Rockland by Knox County Sheriff’s Office Detective Dwight Burtis and Detective Lt. Reginald Walker. The district attorney’s office filed criminal charges of aggravated assault and endangering the welfare of a child against Merrifield on Friday.

According to an affidavit filed in Knox County Unified Court by Detective Burtis, a woman contacted him on May 24 with questions about domestic violence and abuse against children. The woman allegedly told Burtis she was reluctant to report any abuse because the man she was talking about had once worked at the Knox County Jail. She would not provide any additional information, and attempts by the detective to contact her soon after the initial conversation were unsuccessful.

Burtis was able to reach the woman in late June, and she met with him again on July 5 and provided him with a memory stick containing a 62-minute video recording, according to the affidavit. The video was recorded by a home surveillance camera, Assistant District Attorney Jeffrey Baroody said Friday.

The video shows Merrifield attempting to strangle a 12-year-old boy six times within the first 10 minutes of the recording, according to the affidavit. On one occasion, the boy is seen convulsing when he is in a headlock applied by Merrifield, according to the affidavit.

The man then appears to knee the boy in the groin and stomach while the child cries out in pain. Merrifield then makes the boy stand with his head against the wall for the next 50 minutes, according to the affidavit.

After police watched the video, Burtis interviewed the boy, who confirmed he had been assaulted by Merrifield, according to the affidavit.

Merrifield also was interviewed and admitted to putting his hands around the boy’s neck and squeezing but said the child was able to breathe, Burtis reported.

Merrifield worked for the county jail as a corrections officer for a few years before being dismissed by the county in 2009, Chief Deputy Tim Carroll said Friday.

When Merrifield made his initial court appearance Friday afternoon, prosecutor Baroody requested bail of $50,000 cash, saying the facts of the case were egregious.

But defense attorney-for-the-day William Pagnano asked for bail of either $20,000 surety or $500 cash. Pagnano argued that Merrifield has no criminal record and has ties to the community and is thus not a flight risk. The attorney said he had not seen the video but that Merrifield still has the presumption of innocence.

Justice William Stokes ended up setting bail at $35,000 cash.

Merrifield said he would apply for a court-appointed attorney to represent him going forward.