Authorities across Europe are hunting a Tunisian man suspected of killing 12 people by driving a truck into a Christmas market in Berlin, as one of his brothers urged him to surrender.
German authorities have issued a wanted notice for Anis Amri and offered a reward of up to €100,000 for information leading to the 24-year-old's arrest - warning that he could be "violent and armed".
One of Amri's brothers has urged him to turn himself in.
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 Arab Spring uprisings.
German media reported several locations were searched overnight, including a house in Dortmund and a refugee home in Emmerich on the Dutch border. Federal authorities have so far declined to comment.
Nearly three days after the attack which left 48 other people injured, the market in the centre of the German capital has reopened, with concrete blocks in place at the roadside to provide extra security.
Organisers decided to reopen the market without party music or bright lighting, and Berliners and visitors have laid candles and flowers at the site in tribute.
The manhunt for Amri prompted police in Denmark to search a Sweden-bound ferry in the port of Grenaa after receiving tips that someone resembling Amri had been spotted, but officers said they found nothing indicating his presence.
An Israeli woman, Dalia Elyakim, has been identified as one of the 12 killed when a truck ploughed into the market in central Berlin on Monday evening, Israeli officials confirmed.
German officials had deemed Amri, who arrived in the country last year, a potential threat long before the attack - 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.
A document belonging to Amri, who according to authorities has used at least six different names and three different nationalities, was found in the cab of the truck.
Family members of Amri, speaking from his hometown of Oueslatia in central Tunisia, were shaken to learn that he was a suspect.
Amri left Tunisia years ago for Europe but had been in regular contact with his brothers via Facebook and phone.