O.J. Simpson’s former sports agent is to write a tell-all book about the retired American football star - including full details of his "late-night confession" to the alleged murder of his ex-wife in 1994.

The sportsman-turned-actor was acquitted of killing Nicole Brown and her friend Ronald Goldman, but was found responsible for their deaths by a civil hearing.

Simpson caused a stir in 2006 when he announced plans to publish shocking new book If I Did It - a hypothetical account of what he would have done if he was responsible for the double murder. The tome was later released after Goldman’s family won a court order preventing Simpson from cashing in on it.

And now Simpson’s ex-agent, Mike Gilbert, is to release How I Helped O.J. Get Away With Murder - a book which he claims will offer new evidence proving that the 60-year-old did in fact murder Brown and Goldman.

Gilbert - who allegedly worked for Simpson for 18 years - also promises to reveal information on his "crucial role in obtaining the not guilty verdict and why he stayed silent for so long", reports Hollyscoop.com.

But Gilbert has dismissed accusations he is cashing in on Simpson’s misfortune - he’s donating a portion of the proceeds from the sale of the book to the Make-a-Wish Foundation.