BERLIN — German prosecutors made clear on Thursday they do not expect to find Madeleine McCann alive, dashing hopes of a miraculous conclusion in a case that has spanned several countries and 13 years, since the girl went missing as a toddler from a resort in Portugal.
After more than a decade of false leads and empty tips, the German authorities said they were investigating a 43-year-old German sex offender, identified by the German news media only as Christian B., on suspicion of murder in connection with the British child’s disappearance.
“We assume that the girl is dead,” Hans Christian Wolters, a prosecutor in Braunschweig, told reporters on Thursday, a day after the authorities broke the news of the investigation on a German public TV show for unsolved crimes. The authorities said new evidence discovered had led them to conclude that Madeleine was likely the victim of homicide.
In 2013, the same show had highlighted the McCann case, urging viewers to call in with any information that might be relevant.
That helped produce leads that pointed to Christian B., who had been living in the Algarve region of southwestern Portugal, where the 3-year-old girl disappeared from her hotel room the night of May 3, 2007, while her parents dined with friends at a restaurant nearby.
However, the comments by German prosecutors put them at odds with police officials in Britain who maintained this week that they were treating the investigation as a missing persons case, and not a murder inquiry. Detectives in London said they received their first tip about the German man after appealing to the public for information in 2017, on the 10-year anniversary of Madeleine’s disappearance.
After the girl’s disappearance, her parents, Kate and Gerry McCann, mounted an international manhunt that included appeals for help from such British celebrities as soccer star David Beckham and the author J.K. Rowling, and promised millions in rewards for information leading to the arrest of her abductor.
But the efforts went nowhere.
An initial Portuguese police investigation failed to produce any concrete leads and only added to the confusion by naming Madeleine’s parents as suspects, drawing widespread criticism.
In Britain, the latest developments blanketed the front pages of broadsheets and tabloids, in some cases crowding out reports of large anti-racism protests on the same day. “Have They Found Who Took Maddie,” the Daily Mail blared, beneath a frozen-in-time picture of a young Madeleine and a newly released photo of a Volkswagen camper the suspect was known to have been using around the time of the abduction.
But alongside the anticipation in some quarters about a potential break in the case was a measure of weariness about the British news media’s fixation on the matter. Some people pointed to news reports 13 months ago about a German man coming under investigation in the disappearance, a revelation that came around the same time the Metropolitan Police Service was applying for more funding from the Home Office to continue its inquiry.
The Home Office said that it was considering an application for new funding for the 2020-21 financial year by investigators in London. The Home Office also said it had given the London police force 292,000 pounds, or $368,000, to cover the cost of the investigation in the previous financial year.
A spokesman for Madeleine’s parents said the latest statements by the police were the most specific to date, but he also urged caution.
“There have there been countless sightings, tipoffs, rumors, assumptions made largely by the media about A or B, which have all suddenly come to nothing,” Clarence Mitchell, the spokesman, said in a radio interview on Thursday morning.
He did not “want to talk about any sense of hope or optimism around this one, given the circumstances,” he added. “But, as I say, in my memory of being involved in the case, the police have never been quite so specific about an individual as they have been in this appeal.”
The McCanns declined to be interviewed, so as to allow the focus to remain on the police request for more information. The German police are offering 10,000 euros, or $11,233, to anyone providing information that helps to solve the case, and have provided a link where photographs or other possible evidence could be submitted.
Germany’s Federal Criminal Police said the tip line had been overwhelmed in the hours since the crime show, “File Number XY Unresolved,” was broadcast on Wednesday.
One of their appeals was for anyone able to help identify the recipient of a phone call that the suspect made the night of Madeleine’s disappearance from the resort in Praia da Luz, Portugal. The call from a Portuguese prepaid cellphone number came from a tower near the resort and went to another number in Portugal.
In December, a German state court convicted Christian B. of the September 2005 rape and robbery of a 72-year-old American woman in her home in Praia da Luz, the Bild newspaper reported. Court records from that case said the perpetrator had lived about two miles down the road from his victim, who was not further identified.
The trial was held in Braunschweig because Christian B. had been registered there since 2014. The Braunschweig prosecutor said the man suspected in Madeleine’s disappearance had lived off-and-on around Praia da Luz from 1995 until 2007. He made a living working odd jobs in restaurants and selling used cars, but also through drug dealing and theft from hotel rooms and vacation homes.
Among the many crimes on Christian B.’s criminal record were several for the sexual abuse of children, according to Germany authorities.
In 2017, he was deported to Germany on a European warrant after his arrest on a different crime, the Braunschweiger Zeitung reported. The man is currently imprisoned in Kiel, Germany, on a separate charge unrelated to the December conviction, the authorities said. That conviction is being appealed.
Mr. Mitchell said the McCanns had “never given up hope” that their daughter may be found alive, “but they are realistic.”
“This is another important chapter in the search for their daughter,” Mr. Mitchell said. “They say that whatever the outcome of this particular line of investigation may be, they do need to know what happened to their daughter to find peace and to bring whoever’s responsible to justice.”
Melissa Eddy reported from Berlin and Benjamin Mueller from London.