The body of Lindsay Birbeck, 47, was discovered by a dog walker wrapped in two plastic bags in Accrington Cemetery on August 24, 2019 - 12 days after she went missing.
She had invited her teenage daughter, Sarah, and Sarah’s boyfriend for tea at 6pm but when she did not return her worried family raised the alarm.
The mother-of-two's attacker had been on the prowl in the woods for lone females and is thought to have killed Mrs Birbeck shortly after she entered the Coppice.
Today (August 12), a jury at Preston Crown Court convicted the youngster of murder after deliberating for more than four hours.
The verdict was returned exactly a year after Mrs Birbeck was murdered.
Sentencing is expected to take place on Friday (August 14).
Her killer - who was 16 at the time - attended a police station several days after the keep-fit enthusiast was found when police released a CCTV clip of a young male pulling a blue wheelie bin behind him on Burnley Road.
He went on to admit dragging the bin from the Coppice on August 17 - with Mrs Birbeck inside - across Burnley Road to the cemetery where he buried her.
But he claimed he was not involved in her death and that a mystery man had approached him in the area with the promise of a large cash reward if he disposed of the body.
He stated: "I have not met this man before. I have not met him since, nor have I had any contact with him.
"He has not paid me any money. He told me that he would leave the money for me near where the body had been at first once everything was clear."
The Crown said the defendant’s account was "implausible fiction".
Shortly before Mrs Birbeck entered the Coppice, another woman said she feared for her safety when a lone male wearing a grey tracksuit and his hood up followed her on her walk.
He was getting closer when she startled him by glancing back and thought he had pulled up after running.
Mrs Birbeck was identified through dental records and a post-mortem examination concluded the cause of death was neck injuries.
Her naked body was heavily decomposed and no evidence of a sexual assault could be found.
Severe compressive force appeared to have been used, according to a Home Office pathologist, which could have been done in several ways including through stamping or kicking – or kneeling on the front of the neck.
An attempt had also been made to cut off a leg, possibly with a saw.
Mrs Birbeck, mother to Sarah, 17, and Steven, 20, had split up from her husband and moved to her home in Burnley Road in March last year after she started a new relationship.