A Russian orthodox priest who spoke out in support of jailed punk band Pussy Riot has been killed.

Pavel Adelgeim, 75, was stabbed to death in his home near the Estonia border, in the city of Pskov.

A 27-year-old man, who police say was acquainted with the priest, has been arrested in relation to the killing. He reportedly stabbed Adelgeim in the stomach, and then stabbed himself after being arrested.

He was then taken to hospital, where authorities waited to question him. Regional lawmaker Lev Shlosberg, the suspect is mentally ill, and had been staying with the priest over the time of his murder.

Speaking to the Dozhd TV channel, Shlosberg said: “[He was] welcomed by Father Pavel and his wife Vera at their home upon a request from a Moscow woman they were familiar with,

“He is a mentally ill person, and maybe his acquaintances hoped Father Pavel’s word would cure his illness.”

The motive for the murder remains unclear.

Adelgeim spoke out in favour of Pussy Riot, the punk band who performed a controversial anti-Putin music performance at Moscow’s Christ the Saviour Cathedral, back in 2012.

He was also jailed during the Soviet rule, and was a well-known critic of the leadership of the Russian Orthodox Church.

In August, Pussy Riot, Maria Alyokhina, Nadezhda Tolokonnikova and Yekaterina Samutsevich, were jailed for two years for staging an anti-Vladimir Putin protest, with a song that mentioned the country’s persecuted LGBT citizens in a Moscow cathedral on 21 February 2012.

In the wake of a scandal caused last year by a protest by Pussy Riot against Russian President Vladimir Putin, which were held in a Moscow cathedral, a law has since passed by the State Duma to criminalise insulting people’s religious feelings.