JERUSALEM (CBSNewYork/AP) — Israeli police say a court has extended the arrest of a 19-year-old American-Israeli Jew suspected in recent bomb threats against U.S. Jewish community centers.

Police say they are keeping the suspect in custody for another week and placing his father under house arrest. A court has banned the publication of their names.

Israeli media say the suspect’s father told the court on Thursday that his son spent hours alone in his room on the computer and that he was unaware of any suspicious behavior.

The suspect’s lawyer argues a growth in his brain may have affected his behavior. Police say his motives are unclear.

The suspect’s arrest followed an Israeli investigation with the FBI and other international law enforcement agencies. The bomb threats stoked fears of anti-Semitism in the U.S.

Israeli police said the suspect made dozens of calls claiming to have placed bombs in public places and private companies, causing panic and “significant economic damage,” and disrupting public order, including by the hurried evacuations of a number of public venues around the world.

The man is suspected of placing threatening phone calls to Australia, New Zealand and also within Israel.

Police said the man, from the south of Israel, used advanced technologies to mask the origin of his calls.

According to the Anti-Defamation League, there have been more than 150 threats against Jewish institutions in 37 states and two Canadian provinces since Jan. 9. The threats were accompanied by acts of vandalism on several Jewish cemeteries.

Last month, a Missouri man was charged in connection with at least eight threats against the ADL headquarters in New York City and JCCs, schools or other facilities nationwide.

Prosecutors said the threats were made in an effort to harass and vilify his former girlfriend.

(© Copyright 2017 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)