A DEPRAVED sex killer serving life for battering a Finnish student to death has admitted a “horrifying” stranger rape 15 years ago.

Jason Dockrill, 46, evaded capture after he attacked the woman in Wanstead Park between November 2 and 5, 2001

Two years later Dockrill killed 23-year-old Suvi Aronen as her distraught mother heard her pleas for help from 1,000 miles away over a mobile phone.

He left her body horrifically mutilated after a chance encounter with the student in an underpass near the A12 and the River Close in Wanstead, during a series of attacks on women.

When he was told he was being arrested for murder Dockrill said, “Yeah, I'm loving it.”

The former building engineer, described as a shy loner, was jailed for a minimum of 25 years after being found guilty of the brutal murder in April 2004.

Dockrill was linked to the sex attack in 2001 last year following a cold case review of the original investigation.

He admitted one charge of rape and two counts of indecent assault when he appeared at the Old Bailey yesterday (Monday May 23) via a video link from Belmarsh Prison.

Prosecuting, Anita Arora said: “He is currently serving a minimum sentence of 25 years for the murder itself and other concurrent sentences for physical assaults on women the same day as the murder in 2003.”

Referring to the DNA techniques that lead to his arrest for the earlier sex attack, she said: “It's a classic cold case my Lord.

“As the scientific technique became more sophisticated and became more able to detect lower levels of DNA they police were able to trace the defendant.”

Dockrill was not on the police system and a man of good character at the time of the rape.

Defending, Natasha Wong said Dockrill has been a serving prisoner at HMP Whitemoor in Cambridgeshire, where he has received mental health treatment on a special unit for dangerous offenders with personality disorders.

Judge Timothy Pontius said: “I will adjourn sentence to July 18 in order that a full and up to date report can be prepared as to the defendant's current state of mental health, prognosis, current treatment and any suggested disposals that might arise from that.

“Plainly, having read the statement of the victim this is a very serious sexual attack.

“Plainly she was in considerable fear of her life.”

He continued: “It was a stranger rape carried out in a park and as we know from the defendant's guilty pleas it consisted not just of the rape but of two serious indecent assaults as well.

“It is fortunate the defendant has decided to change his plea today and saved the victim from having to relive these horrifying crimes.”

Dockrill, formerly of West Road, Stratford, admitted one count of rape and two of indecent assault.

He is currently not due for parole until 2028.

Miss Aronen, originally from Tampere in Finland, was expected to get a first-class degree in cultural and media studies at the University of East London that year.

She was due to marry a 25-year-old Englishman Ben Lancaster, who she had met in Finland where he worked as a teacher.

They were planning to return to her homeland to live in Helsinki after she graduated.

By a cruel twist of fate she was only in the area because she took a different bus home, the 366, to enjoy the sunny weather in the park.

She was last seen carrying her rucksack towards the underpass followed by bald-headed Dockrill.

Her mother Sirpa Aronen called her at 6pm and heard her daughter being brutally attacked.

She said in a police statement: “I heard Suvi crying in Finnish and English, 'Go away' and 'Don't hurt me'.

“I also heard her crying.

“I heard her mutter and mumbling and understood that someone else was present.

“When I called Suvi and heard her crying I knew that something evil was taking place.”

Dockrill, who had a happy childhood at his family home in Stratford, claimed he was picked on at Trinity Secondary school in Canning Town and enjoyed bullying smaller children in turn.

He joined the army cadets at school in Canning Town and told one psychiatrist he collected deactivated weapons, German memorabilia and skulls.

He also claimed to have enjoyed torturing and stringing up animals - even boasting about tying a firework to a rabbit on a skateboard.

Detectives found hundreds of drawings of skulls and daggers on sketchpads in his room at home.

Sentencing him for the murder of Miss Aronen the then Recorder of London, Judge Michael Hyam said: “Your conduct was wicked and without remorse and I can find no mitigating factor which even begins to excuse your conduct.

“I regard you as a danger to women and consider you are likely to remain so for a long time if not indefinitely.”