Police investigating the murder of a church organist who died after he was attacked on Christmas Eve say they still do not know why he was killed.
Detectives admitted they have not established a motive for the murder of lay preacher Alan Greaves, who died after being attacked on his way to midnight mass in High Green, Sheffield.
Detective Superintendent Matt Fenwick was speaking as he released CCTV footage of two men his officers want to speak to.
The footage was captured on a camera near the scene shortly before the incident, Mr Fenwick said.
The 68-year-old grandfather was making his way to St Saviour's Church from his home a few hundred yards away when he was subjected to the brutal attack.
He died from severe head injuries three days later.
Speaking at a press conference in Rotherham, the detective said: "I still have not established a motive for the attack. Alan retains all his property. Nothing is missing and my inquiry remains very open in relation to identifying a possible motive for this attack."
Mr Fenwick said there was nothing in the victim's personal life which would point to a motive.
He said more than 50 officers are working on the case.
Mr Fenwick said the two people in the footage "may be able to assist us with our inquiries."
He said: "If you are either of these two people shown on the footage then please contact the incident room as soon as you can.
"If you know, or can identify either of these two people, please pick up the phone and tell us what you know.
"I am absolutely convinced that someone out there knows what has happened to Alan Greaves.
"I am absolutely convinced that someone will look at this footage and know who these people are - a mum, a dad, a brother, a sister, another relative, a close friend.
"Alan Greaves deserves your help. Alan Greaves's family deserves your help. Please make that call."
The detective said: "Alan was a loving, caring, husband, father and grandfather who was well-loved and respected by all who knew him."