‘Evil’ killer William Harold Matheson has been released after almost two decades in prison

A convicted killer has been released from prison after serving almost two decades over the brutal murder of his teenage ex-girlfriend.

A “completely evil” man has been released from jail after serving almost 20 years behind bars for murdering his teenage ex-girlfriend who he stalked before strangling her to death and then dumped her body inside a cricket bag at a Sydney unit block.

William Harold Matheson was jailed in 2006 for the brutal killing after he became obsessed with his ex-partner Lyndsay Van Blanken, 18, and flew into a jealous rage after she broke up with him due to his “controlling” nature.

Trainee animator Lyndsay Van Blanken, 18, was last seen boarding a train at Bondi Junction in the early evening on November 24, 2003. Picture: Justin Lloyd

After she became engaged to American hairdresser Brandon Leonard, Matheson stalked and strangled the gifted visual artist, dumping the young woman’s body in the storage room of a Coogee unit block in Sydney’s eastern suburbs in 2003.

It was not discovered for six weeks and police only found the deceased teenager after neighbours complained about a foul smell.

Ms van Blanken had recently got engaged to an American hairdresser. Picture: Justin Lloyd

William Matheson as convicted of killing his ex-girlfriend after she broke up with him.

Ms Van Blanken was a talented visual artist.

A lock of the victim’s hair was taped into her diary, alongside a lock of her killer’s hair.

Matheson was sentenced to 25 years in jail and has now been released on parole after serving 19 years in prison. His first parole application last year was refused.

He will be monitored 24-hours a day and will live in Randwick with his parents. The convicted killer is forbidden from contacting Ms Van Blanken’s family.

An undated photo of Matheson who has been released from prison after serving almost 20 years.

Ms Van Blanken was just a teenager when she was murdered.

Ms Van Blanken’s finance Brandon, with one of her pet rats. Picture: Stephen Walton.

“He decided if he couldn’t have her no one else could,” the victim’s mother Cynthia said of her daughter’s killer.

She described Matheson, a cellist, as a “monster”, and said she believed he would offend again.

“I think he’s completely evil,” Cynthia told 9 News. “He has no conscious, he has no feelings and he’s so smart.”

The pair met when Matheson played cello at Ms Van Blanken’s mother’s wedding two years before the teenager’s tragic murder.