Image: Martti Kainulainen / Lehtikuva

Helsinki police on Tuesday asked a court to remand in custody Michael Penttilä, a man known as the 'serial strangler', on suspicion of murder. Iltalehti was the first media to report on the move.

A police statement on Tuesday said that Penttilä is suspected of murder because the preliminary investigation indicated that there are grounds to suspect that the "homicide was carefully planned and the crime as a whole could be considered especially serious".

Police said the victim, a 52-year-old woman, was found in an apartment in the Kallio neighbourhood after the building's caretaker went to check on a strange smell reported by neighbours. Police suspect the woman had been dead since 13 April.

The woman's body was discovered on 4 May, and police detained Penttilä on 6 May after their initial inquiries led them to his door in the Siltamäki district of north Helsinki. Ilta-Sanomat reported eyewitness accounts from neighbours who said police had come to apprehend Penttilä.

Long criminal history

Penttilä, who changed his name from Jukka Lindholm, was born in Oulu in 1965 and has three previous convictions for homicides, but none of them were classified as murder.

His criminal career began in 1985 when he strangled and killed his mother. He confessed to the offence one year later in 1986 after he was detained over the strangling death of a 12 year-old girl. He was convicted of the girl's death in 1987.

Penttilä has served several prison sentences, but was freed from his latest prison stint in late 2016. Last year police suspected him of plotting a murder but released him due to a lack of evidence following a preliminary investigation . Police had suspected Penttilä was planning to strangle a 17 year-old girl who lived in his building.

Following a request from Finland, the FBI analysed the Penttilä cases and likened his actions to that of a serial killer.

Criminal law professor Matti Tolvanen was asked how it was possible that such an violent individual is permitted to live free, outside a prison.

"This is the Finnish [legal] system," Tolvanen said. "If a person does not receive a life sentence, he [or she] must be released when a sentence is [fully] served. In Penttilä's case, he was convicted of manslaughter and served his sentences."