DETECTIVES investigating the brutal murder of a wealthy businessman today admitted there could be a sexual element to the attack.

Mr O'Brien was found in the bedroom of his £300,000 home on the Old Woodyard, Midgley, near Wakefield, at 5pm last Wednesday, by his live-in girlfriend Jan Charlton.

Mr O'Brien lived in Holme Terrace, Townsendfold, Rawtenstall, until three or four years ago.

Det Ch Supt Paul Johnston, said: "When Danny's body was found he was naked. That indicates there might be a sexual motive to this crime."

Officers were yesterday stopping traffic and questioning people in a bid to piece together what happened a week ago.

Mr O'Brien made his money by selling his gas repair and fixture company to British Gas. An axe was embedded in his head when he was found.

His girlfriend was heard screaming by neighbours after returning to the house with her four-year-old daughter.

Mr Johnston said there was no sign of a break-in and that in his opinion Mr O'Brien knew the killer; it was possible some of his past associates may be "a little aggrieved" as a result of business dealings with the entrepreneur.

He said the four-bedroom house was for sale and was keen to speak to any prospective buyer. Mr Johnston said he was keen to trace a man seen to knock at Mr O'Brien's door on the morning of the murder and a man in a light coloured Ford Mondeo parked in the street.

Ms Charlton was distressed and being comforted by relatives, added the detective.

A former neighbour in Holme Terrace, Rawtenstall, where "Danny" is remembered as an outgoing, friendly personality, said he used the cottage mainly as a weekend home and had taken a number of girlfriends back there. "He was just a nice, easy-going lad."

Mr Johnston said no one had been ruled out of the murder inquiry yet.

Forensic officers have spent a week sifting through the contents of Mr O'Brien's house and garage, which was littered with toys belonging to Mrs Charlton's daughter, Amy.

Mr Johnston said he was now confident that the axe used in the attack was taken from the house.

"Fortunately Danny appeared to be a very meticulous record keeper. One cabinet was stuffed full of names and addresses which will save us a lot of time."

Mr Johnston refused to speculate on rumours that Mr O'Brien had been found handcuffed and gagged.