A £70,000 reward has been put up in a bid to catch the killers of a wealthy businessman.
The murder of 57-year-old John Luper at his luxury home at Alwoodley, Leeds, late on February 16 was shown on last night's Crimewatch programme.
The appeal produced 40 calls to the studio, two of which police said revealed new information.
Mr Luper, a prominent businessman and Freemason, had many friends and colleagues in Huddersfield.
He made his fortune in the family clothing business in Leeds but had recently been involved in several other businesses, including serving as a non-executive director of a football and entertainment agency.
Inquiries to trace the gang responsible for Mr Luper's death have been focused on Liversedge and Bradford.
Mr Luper was taking his dog for a walk when he was attacked at 11.30pm.
He was then dragged back to his own home with no signs of a struggle so police believe he had been quickly incapacitated by his attackers.
His wife, Lyician, 20-year-old daughter Liza Rose and the family's au pair had been tied up by the intruders and when they managed to free themselves at 1.45am, they found Mr Luper in the breakfast room next to the kitchen.
He was dead and a post mortem later revealed he had been asphyxiated.
Police believe one of the four masked intruders may have been a woman and they knew the layout of the house and garden.
One of the masked men showed he had a conscience.
Det Supt Bill Shackleton, who is leading the investigation, said:
"Despite the initial violence shown, one attacker showed considerable compassion towards the women.
"This man is at least 6ft with a powerful build.
He said things like "I wish I hadn't come here, I'm not a bad man, I'm so sorry and will you forgive me?"
"I see this man as the reluctant robber. Perhaps events had not gone as planned or it may be he realised John had died.
"He is the only person who can answer these questions."
Mr Luper and his family are thought to have been targeted for their wealth rather than any personal reason.
About £1,000 cash and a wallet, a purse, jewellery and watches worth a total of £20,000 were taken.
Mr Luper was a close friend of former Huddersfield Town chairman David Taylor and had been a guest at Town games.
Contact the police incident room number on 0113 241 3350 or Crimestoppers in confidence on 0800 555111.