Mr. Najib and his wife, Rosmah Mansor, have been barred from leaving the country while investigations continue. Authorities raided residences associated with the couple nine days after the election and confiscated more than 350 boxes and pieces of luggage containing luxury handbags, jewelry, watches and $28.6 million in cash.
Mr. Mahathir told reporters on Friday that the authorities were now seeking Mr. Low over activities related to the fund. Mr. Low, a Malaysian, helped set up 1MDB after its founding in 2009 and, though he never held an official position at the fund, has been described by authorities in the United States as a key figure in moving money out of it.
“We are trying to arrest Jho Low,” the prime minister told reporters. “He is not in the country and we don’t have extradition rights in the country where he is staying.”
When asked what country that was, he said, “many countries.”
Mr. Low was a friend of Mr. Najib’s stepson, Riza Aziz, whose production company, Red Granite Pictures, later used money said to be from 1MDB to produce Hollywood movies, including “The Wolf of Wall Street.”
Red Granite reached an agreement in March to pay $60 million to settle an assets seizure lawsuit filed by the United States Justice Department.