Detective Superintendent Jason Murphy is appealing for information on the murder of Piotr Krowka in Maghera.
The 36-year-old man was homeless at the time of his murder and his body was discovered in a former parochial house on the Glen Road on April 3.
He had been living in Maghera "on and off" since 2005 and had fallen on hard times, sleeping in derelict buildings, DS Murphy said.
The senior officer believes Mr Krowka was attacked and killed on or around Easter Saturday, March 30.
