German prosecutors believe Madeleine McCann is dead and are investigating a child sex predator on suspicion of her murder.

The suspect, a 43-year-old German national named in media reports as Christian Brueckner, is reportedly serving a seven-year prison sentence for the rape of a 72-year-old American woman in Portugal in 2005.

He is known to have lived on the Algarve coast and his Portuguese mobile phone received a half-hour phone call in Praia da Luz around an hour before Madeleine, three, went missing on May 3 2007.

Launching an appeal on Wednesday night, Scotland Yard said he was believed to have been living in a distinctive early 1980s VW T3 Westfalia camper van at the time and re-registered a 1993 Jaguar XJR6 in someone else’s name the day after her disappearance.

The force’s Operation Grange, which has received £12.3 million in funding up since it was launched in 2013, still considers the case a missing person inquiry because there is no “definitive evidence whether Madeleine is alive or dead”.

But Hans Christian Wolters, a spokesman for the Braunschweig public prosecutor’s office, said the suspect is being investigated “on suspicion of murder”, adding: “We are assuming that the girl is dead.

“With the suspect, we are talking about a sexual predator who has already been convicted of crimes against little girls and he’s already serving a long sentence.”

German newspaper Braunschweiger Zeitung reported the suspect, who has been partially identified as Christian B by local media due to the country’s strict rules on the naming of criminals, was convicted of rape in Braunschweig District Court in December last year.

Der Spiegel reported he is serving a prison sentence in Kiel, having been initially extradited from Portugal in 2017 and convicted of drug trafficking.

The German magazine said his criminal record contains a total of 17 entries, including child abuse while he was still a teenager, and published a pixelated picture of him apparently taken from Facebook.

It comes after Christian Hoppe, from Germany’s Federal Criminal Police Office (BKA), told the country’s ZDF television channel on Wednesday night German police have not ruled out a sexual motive for the alleged crime against Madeleine.

He said that the suspect may have broken into an apartment in the Ocean Club complex, where Madeleine was on holiday with her parents, Kate and Gerry McCann, and her twin siblings Sean and Amelie, before spontaneously kidnapping her.

A BKA appeal said: “There is reason to assume that there are other persons, apart from the suspect, who have concrete knowledge of the course of the crime and maybe also of the place where the body was left.”

Both vehicles linked to the suspect have been seized by German police, who said there is information to suggest the suspect may have used one of them in the alleged offence.

The BKA is asking for other potential victims to come forward, while an appeal on German Crimewatch-style programme XY said the suspect was linked to houses in Portugal, including one between Praia da Luz and Lagos.

German prosecutors said he was living in the Algarve between 1995 and 2007, where he worked jobs, including in the catering business, but funded his lifestyle by committing crimes, such as thefts in hotel complexes and apartments, as well as drug dealing.

Scotland Yard revealed the “significant development” in a joint appeal with the BKA and the Portuguese Policia Judiciaria (PJ), including a £20,000 reward for information leading to the conviction of the person responsible for Madeleine’s disappearance.

DCI Mark Cranwell said more than 270 calls and emails had been received by Thursday afternoon.

“We are pleased with the information coming in, and it will be assessed and prioritised,” he said.

“We continue to urge anyone with information to come forward and speak with us.”

The Met’s investigation has identified more than 600 people as potentially significant and was tipped off about the German national, already known to detectives, following a 2017 appeal 10 years after she went missing.

She vanished shortly before her fourth birthday, while her parents were eating dinner with friends at a nearby tapas restaurant, and would have turned 17 last month.

Kate and Gerry McCann, from Rothley, in Leicestershire, welcomed the latest appeal in a statement which said: “We will never give up hope of finding Madeleine alive, but whatever the outcome may be, we need to know as we need to find peace.”

Clarence Mitchell, a spokesman for Madeleine’s family, said her parents felt the development was “potentially very significant” and that he could not “recall an instance when the police had been so specific about an individual” in the 13 years since she disappeared.

He told BBC Breakfast: “Of all the thousands of leads and potential suspects that have been mentioned in the past, there has never been something as clear cut as that from not just one, but three, police forces.”

Downing Street said the latest developments appeared to be significant and added that Number 10’s thoughts were with the McCann family “who have had to endure so much”.