A US federal appeals court has upheld R. Kelly's 20-year prison sentence over child pornography and other crimes, rejecting the R&B singer's defense that the case was filed too late.Kelly was sentenced in February last year but his lawyers argued the statute of limitations had passed by the time he was charged, a defense the Chicago court rejected on Friday."For years, Robert Sylvester Kelly abused underage girls. By employing a complex scheme to keep victims quiet, he long evaded consequences," judge Amy St. Eve wrote in the ruling by the three-panel bench."Those crimes caught up with him at last. But Kelly -- interposing a statute-of-limitations defense -- thinks he delayed the charges long enough to elude them entirely. The statute says otherwise, so we affirm his conviction."Kelly, 57, is already serving a 30-year sentence he received after a Brooklyn jury in a separate federal trial convicted him on racketeering and sex trafficking charges.The two sentences would be served concurrently, with all but one year taken at the same time, adding up to a maximum of 31 years in jail.His lawyer Jennifer Bonjean told US media that Kelly would appeal the decision before the Supreme Court."We are disappointed in the ruling but our fight is far from over," Bonjean said in a statement.- Anonymous tapes -Kelly was convicted by a New York court in September 2022 on six of 13 counts: three of producing child pornography and three of enticement of a minor.The federal conviction in Chicago came one year later and was widely seen as a milestone for the #MeToo movement: it was the first major sex abuse trial where the majority of the accusers were Black women.It was also the first time Kelly faced criminal consequences for the abuse he was rumored for decades to have inflicted on women and children.A Chicago native who soared to global celebrity on a burst of 1990s megahits including "I Believe I Can Fly", Kelly became one of R&B's biggest stars, and dodged censure despite a dubious personal life -- including his ultimately annulled marriage to 15-year-old protege Aaliyah.In the early 2000s, Chicago reporter Jim DeRogatis anonymously received two tapes that appeared to show Kelly having sex with young girls.The artist was indicted for child pornography but following years of trial delays -- during which he continued to tour and record -- Kelly was acquitted on all counts in a controversial trial.DeRogatis and other reporters continued to publish allegations of assault and abuse, however, as two women in Atlanta founded the "Mute R. Kelly" movement, which encouraged boycotting his music.It wasn't until January 2019, when a Lifetime docuseries once again aired the allegations, that a sea change began.His label dropped him and as outrage boiled over, fresh legal action brewed: prosecutors levelled state charges against him after which federal prosecutors in both Illinois and New York indicted Kelly.