Hussein Khavari, of uncertain age and origin, has admitted to the deadly night-time attack on medical student Maria Ladenburger, 19, in October 2016 in the university town near the French border.

Khavari pushed her off her bicycle as she was riding home alone from a party, then bit, choked and raped her and left her on the bank of a river where, an autopsy showed, she drowned.

He was arrested seven weeks later after a huge manhunt. Police had found a black hair partially dyed blond at the scene, then spotted Khavari by his hairstyle on security camera footage and linked him to the crime using his DNA.

As the crime sparked public anger and revulsion, social media users posted sarcastic "thank you" messages to Chancellor Angela Merkel over her liberal policy that brought more than one million refugees and migrants to the country.

Prosecutor Eckart Berger reminded the two jurors sitting alongside three judges that "on trial is a criminal offender and not Germany's refugee policy".

- Jailed in Greece -

Khavari arrived in Germany, without identity papers, in November 2015, near the peak of the refugee influx, as an unaccompanied minor claiming to be 16 or 17 years old and hailing from Afghanistan.

A police officer told the court that Khavari's cellphone and social media accounts suggested he had long lived in Iran.

Khavari was sent to live with a German host family in the picturesque town on the edge of the Black Forest, went to a local school, learnt German and received state benefits.

It emerged only after his arrest that he had already committed a violent crime in May 2013 in Greece, where he pushed a woman off a cliff on the island of Corfu, leaving her badly injured.

He was sentenced there in February 2014 to 10 years jail for attempted murder but was granted a conditional release from Greece's overcrowded jails in October 2015.

He fled via Austria to Germany, where authorities knew nothing of his criminal past because Greece had only issued a nationwide warrant, and because no match was detected in an EU-wide fingerprint data base for asylum seekers.

Khavari was initially tried as a juvenile offender, but prosecutors have tabled expert opinions that estimate him to be older than 21.

One assessment based on X-rays of his bone structure found him to be 22 or 23 years old, while a dental analysis estimated him to be aged between 22 and 29.

If a higher age is accepted by the court, the defendant could face a life term under adult criminal law, which usually translates to 15 years behind bars but can be extended for convicts deemed to pose an ongoing threat to the public.

Khavari on the second day of court hearings in September admitted to the crime, claiming he had heavily abused alcohol and drugs at the time.

He has also claimed that his father died long ago in a battle against Afghanistan's Taliban.

The presiding judge, Kathrin Schenk, in December dialled a number on Khavari's cellphone and reached his father, who told her through an interpreter that he was living in Iran.afp