LOS ANGELESBBCMichael Jackson could have made more than $1.1bn on his This Is It comeback tour, a financial expert has told a court at the singer’s wrongful death trial in the US. Accountant Arthur Erk said he used conservative estimates to determine Jackson’s earning potential. But his calculations did not include the singer’s $400m debt.Katherine Jackson, who is suing music promoters AEG Live for $40bn, was heard for the first time in court.In a video statement, the singer’s mother said she was surprised when Jackson announced the This Is It concerts in London. “He didn’t want to be doing the moonwalk on stage when he’s over 50,” she said in a short clip of her out of court testimony. But Mr Erk, who has worked with musicians including Britney Spears and rock band Kiss, said Jackson had considered a Las Vegas show based on his music and archive footage. “Demand was so wild that he probably could have charged more for tickets and still sold out,” Erk told the court. Jackson had signed on for 50 shows in London before he died in June 2009, but contracts for the shows indicated a longer 37-month tour was a possibility.