Signed Princess Diana sketch by Michael Jackson to be sold in collection valued at over £70m

A sketch of Princess Diana is among a collection of more than 100 drawings by Thriller and Bad star Michael Jackson that will be sold for charity, a private collector has said. The collector, drug counsellor Joseph McBratney, has original drawings made by the self-styled King of Pop, which he says have been authenticated by an autograph authentication service and valued at in excess of $100 million (£70m).

McBratney reportedly collected the drawings "little by little" over the years via purchases from eBay. He even acquired some of the sketches by the singer, who died in 2009, from a Mexican woman, who came into possession of them while working for Sony.

McBratney said that the autograph authentication service found the drawings to be genuine. He plans to sell the collection, which features portraits of famous faces including Charlie Chaplin, The Beatles, Abraham Lincoln, Barack Obama, John F Kennedy, James Dean, Marilyn Monroe, Charlie Chaplin, Bart Simpson, Peter Pan, Mickey Mouse, Snoopy and Garfield, as well as some self-portraits, to raise funds for his drug rehabilitation centre for young people in Florida.

"It's a very big responsibility for me," he told The Telegraph. "I could have sold them years ago, but at that point there weren't enough in one collection for healing the world and saving the children. Now they are together," McBratney said of a collection he called "an incredible body of work".

"In-between shows, he [Michael Jackson] couldn't wander about or go shopping like normal people, so my understanding is that he just drew the portraits then, to pass the time," he said. McBratney added that he had been offered lucrative amounts for each drawing, but he wanted to sell the works as a collection to better benefit his drug-rehabilitation centre.

''It would be a shame for this beautiful property to be anything else but a healing property for suffering kids and adults who would never have the chance to be in recovery or treatment,'' he was quoted as saying by the New York Post's Page Six column.