Ex-Irish international and current Leeds United manager, Mr David O'Leary, has been the target of a series of "menacing and chilling" letters which apparently contain threats to his wife.
West Yorkshire Police detectives told a press conference that Mr O'Leary has now been sent seven letters by an anonymous writer.
Detective Superintendent Eddie Hemsley said the letters made certain "demands" of Mr O'Leary and threatened "serious harm" to his wife Joy if these were not carried out.
Mr Hemsley said he would not go into detail about what the demands are but added: "It was a demand in relation to the club and if it was not done then serious harm would come to his wife."
He added: "He (the letter writer) has had opportunities to carry out the threats and he has not done so but there is always that risk.
Mr Hemsley said the letter writer had been identified with a particular "cause", but he would not elaborate.
The first letter arrived at Leeds’s Elland Road ground shortly after the start of the first trial of Leeds United players Lee Bowyer and Jonathan Woodgate.
It was posted on February 14, 2001.
The last in the series was posted on December 18 and Mr Hemsley spoke in front of a 2ft wide blown-up image of the handwritten envelope.
He said postmarks showed six of the letters were sorted in Doncaster, South Yorkshire, and were therefore posted in either the Doncaster or Lincoln postal areas.
The other letter was posted in the Nottingham area, Mr Hemsley told a news conference at Holbeck police station, about a mile from the Leeds United ground.
PA