ROCKLAND — A South Thomaston woman charged with murder in the beating and strangulation death of an Owls Head woman pleaded not guilty by reason of insanity during a court hearing Wednesday.

Sarah Richards’ attorney entered the plea on her behalf during a hearing that lasted about one minute in the Knox County Courthouse.

Sarah Richards is led out of the courtroom after pleading not guilty to murder in May. Stephen Betts/The Courier-Gazette

Assistant Attorney General Leane Zainea filed a motion Wednesday for Richards to undergo a forensic evaluation. The prosecutor also requested that the report from the State Forensic Service not be impounded when it is completed because Richards is pleading not criminally responsible because of insanity in the slaying of Helen Carver, 83.

Justice Bruce Mallonee signed the order for the evaluation to be done within 45 days, with a report to be issued within 60 days.

Richards had pleaded not guilty to murder and theft charges in Knox County Superior Court on May 28.

If the case goes to trial, the jury will first determine whether Richards killed Carver. If the jury finds her guilty, jurors would then be asked to determine whether she is criminally responsible.

Richards has been held without bail at the Knox County Jail in Rockland since her arrest Feb. 22, a day after Carver’s death.

An affidavit filed by state police earlier this year said that Richards had stopped at the home of her ex-husband, either Feb. 20 or  21, and asked him “if he would be willing to kill someone.”

The man told police he thought she was kidding, but then realized after he learned about Carver’s death that he had no doubt that Richards was asking him if he would be willing to take part in killing Carver.

Carver’s son, Robert Carver, had talked with his mother by telephone shortly before 11 a.m. Feb. 21, and in the conversation she had told him that Richards had stolen her debit card. The Knox County Sheriff’s Office confirmed that the Owls Head woman had contacted the office Feb. 14 about the theft.

A Knox County deputy had contacted Richards and was scheduled to interview her Feb. 22.

Witness reports said that Richards and her boyfriend were seen leaving the area of Carver’s home at about 11:30 a.m. Feb. 21, according to the police affidavit.

Her son found his mother dead in the home shortly after 1 p.m. Feb. 21, after he was unable to reach her again by phone. Carver lived alone at the South Shore Drive home after her husband’s death.

Richards initially told police that she had been at the house to shovel snow and went inside and Carver was in good shape when she left, according to the affidavit. However, she later changed her story and said she went inside and Carver was already dead. Richards said she provided lifesaving efforts and left, police said.

Richards then said when she went inside the house, Carver was upset over the stolen debit card and that the elderly woman “came at her.” Richards said she then lunged at Carver and tackled her into an entertainment center. Richards also admitted to striking Carver in the head with a tool. The type of tool is not stated in the police report, but police obtained a warrant from the court to examine a shovel that Richards owned for any signs of blood.

Richards said she put her hands around Carver’s neck to determine if she had a pulse.

The affidavit says that the Medical Examiner’s Office determined the cause of death as blunt force trauma with signs of strangulation.

Another affidavit said that Verizon records from the phones of Richards and her boyfriend, Jimmy Wellman, could help develop a timeline of events leading up to the murder. The phones were seized the morning of Feb. 22 from the truck that Richards and Wellman were driving.

A murder conviction carries a minimum mandatory sentence of 25 years in prison in Maine.

The trial is tentatively scheduled to be held in August 2020 and is expected to last one week.

Richards has a long criminal record. She was convicted of stealing more than 100 lobster crates from Fox Island Lobster in Cushing in 2013. She had worked at the business.

She received a nine-month jail term in 2016 for unlawful trafficking in drugs. In June 2017, she was sentenced to 30 days in jail for violating her probation for the drug conviction.

She was charged with theft in 2012 by Waldoboro police. In 2013, she served seven days in jail for violating a condition of release.

In 2006, Richards was sentenced to five days in jail for violating probation for illegal importation of drugs. In 2004, she was sentenced to 48 hours in jail for theft.