The fingerprints of the Tunisian man being sought over the Berlin truck attack have been found in the vehicle's cab, Germany's interior minister has confirmed.
Thomas de Maiziere said the fingerprint discovery strengthens Germany's case linking Anis Amri, 24, to Monday's attack, which left 12 people dead and 48 others injured after the truck ploughed through a Christmas market.
German authorities have issued a wanted notice for Amri, describing him as potentially violent and armed.
Mr de Maiziere spoke after visiting Germany's federal criminal police office alongside chancellor Angela Merkel.
German authorities have offered a reward of up to 100,000 euro (£84,000) for information leading to Amri's arrest.
Islamic State (IS) has claimed responsibility for the carnage in the German capital.
Mr de Maiziere said: "We can tell you today that there are additional indications that this suspect is with high probability really the perpetrator.
"Fingerprints were found in the cab, and there are other, additional indications that suggest this.
"It is all the more important that the search is successful as soon as possible."
In Tunisia, one of Amri's brothers urged him to surrender to authorities.
Abdelkader Amri said: "I ask him to turn himself in to the police. If it is proved that he is involved, we dissociate ourselves from it."
He said Amri may have been radicalised in prison in Italy, where he went after leaving Tunisia in the wake of the 2011 Arab Spring uprisings.
Amri's mother said her son had shown no signs of radicalisation, and questioned whether he was really the attacker.
Speaking in the central Tunisian town of Oueslatia, Nour El Houda Hassani said poverty drove Amri to steal and to travel illegally to Europe.
She said Amri spent time in an Italian prison and in Switzerland before reaching Germany.
"I want the truth to be revealed about my son," she said.
"If he is the perpetrator of the attack, let him assume his responsibilities and I'll renounce him before God. If he didn't do anything, I want my son's rights to be restored."
Tunisian police who interrogated the family on Wednesday took away her telephone and are studying her communications with her son, she said.
German officials put out an arrest warrant for Amri, who according to authorities has used at least six different names and three different nationalities, after finding a document belonging to him in the cab of the market attack truck.
German authorities had deemed Amri, who arrived in the country last year, a potential threat long before the attack this week - and even kept him under covert surveillance for six months this year before halting the operation.
They had been trying to deport him after his asylum application was rejected in July but were unable to do so because he lacked valid identity papers and Tunisia initially denied that he was a citizen.
In Berlin, the market hit by the attack has now reopened - with increased security measures - in a signal of the city's resilience.
At the market outside Berlin's Kaiser Wilhelm Memorial Church, police placed concrete blocks at the roadside to provide extra security. In a solemn tribute to the victims, organisers decided to do without party music and bright lighting, and Berliners joined visitors in laying candles and flowers at the site.
An Israeli woman, Dalia Elyakim, and 31-year-old Fabrizia Di Lorenzo of Italy were among the 12 killed in the market attack, their countries said. Ms Di Lorenzo had lived and worked in Berlin for several years.
Two Americans were among the wounded, US state department spokesman John Kirby said.