The U.S. is investigating whether the theft of $81 million from a Bangladesh central bank account at the New York Fed is linked to North Korea because of the similarity of the hack to an earlier breach of Sony Pictures Entertainment, two people familiar with the matter said.

There's no indication that charges would be filed soon, said one of the people, both of whom asked not to be identified because the matter wasn't public.

Some cybersecurity experts have concluded last year's theft from the Bangladesh central bank's account was done with some of the same hacking tools used in the 2014 attack on Sony Pictures, the maker of the movie "The Interview," which poked fun at North Korea Supreme Leader Kim Jong-Un. The Sony hack, linked to North Korea by the FBI, was followed that year by a blackout of North Korea's internet that a U.S. lawmaker said was retaliation, without saying who was responsible for the outage.