PETER Tobin is back behind bars after being taken to hospital for a suspected stroke.

The serial killer is understood to have been taken to Edinburgh's Royal Infirmary after being found slumped in his cell on Sunday afternoon.

Doctors are said to have been left baffled by his mystery health problem, and the 69-year-old was sent back to Saughton prison last night.

Tobin is serving life sentences for the murder and rape of Polish student Angelika Kluk, schoolgirl Vicky Hamilton and Essex teenager Dinah McNicol.

He was convicted of murdering 23-year-old Angelika at a church in Glasgow in 2006.

A year later the bodies of Dinah McNicol, 18, and Vicky Hamilton, 15 from Falkirk, were found in the garden of his old house in Margate.