BRUSSELS (AP) – Belgian authorities are focusing a new search on a man known to have traveled with key Paris attacks suspect Salah Abdeslam, who was captured last week in Brussels, officials said Monday.

Federal prosecutors appealed to the public for information about 24-year-old Najim Laachraoui, who allegedly traveled to Hungary with Abdeslam before the Nov. 13 carnage, and has been traced to safe houses under a false name.

Laachraoui was checked by guards at the Austria-Hungary border on Sept. 9 while driving in a Mercedes with Abdeslam and one other person, Belgium’s federal prosecutors said in a statement.

Laachraoui, whose nationality wasn’t disclosed, had traveled to Syria in February 2013, prosecutors said. It wasn’t clear when he returned to Europe.

Using a false identity, Laachraoui also rented a house under the name of Soufiane Kayal in the Belgian town of Auvelais that was allegedly used as a safe house, where prosecutors said traces of his DNA were found. The house was searched Nov. 26.

Laachraoui is “someone who must explain himself,” Belgian prosecutor Frederic Van Leeuw said, stressing that “clues” don’t amount to proof.

Investigators have struggled with the complexity of the Paris attacks case.

“We are far from putting the puzzle together,” Van Leeuw said. He stressed that the public should come forward with information they may have.

Investigators don’t yet know the “exact path” taken by Abdeslam, who had crisscrossed Europe ahead of the Paris bloodbath and then fled the scene, a Belgian federal prosecutor said Monday.

Abdeslam, suspected as a logistician in the attacks that killed 130 people, was arrested Friday after a four-month manhunt in the same neighborhood in Brussels where he grew up.

Van Leeuw told reporters at a news conference in Brussels that investigators hope to find out the details of Abdeslam’s actions between the Nov. 13 attacks and his arrest, “if he decides to tell us.”

Abdeslam, 26, a French citizen who grew up in Brussels’ heavily immigrant Molenbeek neighborhood, slipped through police fingers on multiple occasions, including the day after the attacks. He was interviewed three times Saturday, the day after his capture – once by prosecutors and twice by an investigating judge – and “wasn’t in great shape” because he had been shot in the leg by police during his capture, Van Leeuw said.

In addition to the Paris attacks investigation, Belgian anti-terrorism prosecutors have worked non-stop on hundreds of other cases – 325 cases last year and nearly 60 new cases so far this year, Van Leeuw said.

His French counterpart, Francois Molins, who was also at the news conference, said his team has 244 anti-terror cases in progress concerning 772 individuals either charged or sought.

“(It’s clear) we have a general threat,” Van Leeuw said.

Abdeslam has a court hearing on Wednesday. France has requested his extradition but Abdeslam’s lawyer says his client will fight the request.

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Elaine Ganley reported from Paris.