PORTLAND – Jurors who heard a tape recording in which the mother of Jeffery “Russ” Gorman said her son admitted shooting a South Berwick woman found him guilty of murder Friday.

Tammy Westbrook became a pivotal figure in her son’s trial when a judge allowed prosecutors to play an audiotape of grand jury testimony on which she recounted how her son confessed in a phone call to shooting Amy St. Laurent in the head.

Westbrook, who testified she doesn’t remember the 22-minute conversation, said after the verdict that her prayers were with St. Laurent’s family. But she denied that her son had a role in the woman’s death. “I know my son is innocent of this crime,” she told reporters. “Justice was not served today.”

St. Laurent, 25, was last seen in Portland’s Old Port district on the night of Oct. 20, 2001. Her body was found seven weeks later in a shallow grave near Westbrook’s house in Scarborough; she was shot once in the head.

The decision by Superior Court Justice Nancy Mills to allow the tape of Westbrook’s Feb. 8, 2002, grand jury testimony as evidence was seen as critical in the trial, since the prosecution’s case against Gorman was entirely circumstantial.

The jury in Cumberland County Superior Court deliberated for about five hours before reaching its verdict. Cliff Strike, Gorman’s defense lawyer, said the judge’s decision to admit the tape could be grounds for an appeal.

“My client never was able to challenge that testimony itself,” Strike said. “You certainly cannot question someone who has no memory.”

Deputy Attorney General Bill Stokes expressed satisfaction with the jury’s verdict, but said he identified with Westbrook’s plight at the trial. “She was living a mother’s worst nightmare,” he said.

During closing arguments Friday morning, Strike told jurors Westbrook was “delusional” and her testimony cannot be trusted. “The woman has no credibility. She’s someone to be pitied and not someone to be believed,” Strike said.

Assistant Attorney General Fern LaRochelle methodically laid out the state’s circumstantial evidence, saying Gorman was the last to see St. Laurent alive and that she was buried a half-mile from his mother’s home in Scarborough.

LaRochelle said it would be quite a coincidence for the body to show up near Westbrook’s home if someone else killed St. Laurent.

Gorman, 23, was arrested four days after the discovery of the body after a standoff with police in his hometown of Troy, Ala.

Closing arguments came a day after Mills took the unusual step of admitting Westbrook’s grand jury testimony.

Westbrook said she spoke to her son the day after the body was found and that he confessed to shooting St. Laurent in the head. At the time, the cause of death had not been released.

Westbrook’s lawyer, Daniel Lilley, unsuccessfully challenged the prosecution subpoena and the admission of the grand jury testimony. He said it would be grounds for appeal if Gorman were to be convicted.