Detectives in three countries have appealed for evidence in relation to the strongest suspect they have had in 13 years to the disappearance of Madeleine McCann, as German authorities said they believe she is dead. Circumstantial evidence has convinced detectives that a 43-year-old German child sex offender and rapist, identified by Portuguese sources on Thursday as Christian Brückner, is their prime suspect as it emerged he has been known to police for years. A major appeal for information on Wednesday has led to new tip-offs in the last 24 hours to police. According to court documents, Brückner was convicted in Germany last year of the rape of a 72-year-old American woman in Praia da Luz, Portugal, in 2005, two years before Madeleine was snatched from the same area. He has a string of convictions ranging from child sexual abuse to theft and drug-dealing. He is also known to have made hotel break-ins, German officials said on Thursday. While German authorities said they believe Madeleine is dead, British police believe no direct evidence of that exists and continue to treat the case as a missing person investigation. She was abducted in May 2007 aged three as her family holidayed in the Algarve. Clarence Mitchell, a spokesman for Madeleine’s parents, Kate and Gerry McCann, said that in the 13 years since their daughter vanished, there had never been a time “I can recall [the police] focusing on one individual”. The development is “potentially very significant”, the McCanns believe. Brückner’s first conviction was in 1994, for a child abuse offence in Germany when he was still a teenager. He fled to Portugal the following year and lived in Praia da Luz. His name was in the Portuguese police system since 2007, it is claimed, but he had not leapt out as a major suspect. The suspect is also understood to have been known to British police. But his potential significance started to emerge only after an appeal on the 10th anniversary of Madeleine’s disappearance in 2017 led to new information. Further inquiries by detectives from Scotland Yard and German and Portuguese police pointed to him as being of potential significant interest. Detectives’ inability to move the case forward led to appeals for witnesses in the three countries. They believe they have significant circumstantial evidence, and are seeking direct evidence to place before a court, it is understood. In Germany, Braunschweig state prosecutor Hans Christian Wolters said the suspect had criminal convictions, including for sexual offences and the abuse of children. He said Brückner had lived in Portugal between 1995 and 2007. “According to our information during this time period, he had various casual jobs in the Lagos region, including in the hotel and catering industry,” Wolters said. “There is further evidence that the suspect boosted his income with criminal acts, including break-ins in hotels and holiday flats, as well as through drug-dealing.” British police say a mobile phone used in the immediate area and shortly before Madeleine’s disappearance was linked to Brückner. His Jaguar car was re-registered to a friend the day after the abduction. At its height, the UK investigation into the disappearance of Madeleine had 600 people of interest. The road to whittling down the 600 individuals involved a joint investigation, with detectives going through rental records in and around Praia de Luz and checking those names against records of paedophiles from across Europe and beyond. German police have “primacy” in the investigation into the suspect and it was the German force that decided now was the time to launch an appeal for information about him. Any suspect who is charged with the murder of a British citizen abroad could be tried before a British court and jury, a former senior prosecutor said. Nazir Afzal, former chief crown prosecutor in the north-west of England, said section 9 of the 1861 offences against the person act would permit a trial in the UK if a suspect was charged with murder: “Legally somebody could be tried in this country … It’s difficult but it has been done before.” British investigators from the Metropolitan police currently have an application into the Home Office for money to continue funding their inquiry, which has cost more than £11m, a government spokesperson confirmed.