The Federal Bureau of Investigation (FBI) asked for crypto industry help in tracking and blocking transactions intended to launder the $1.5 billion stolen from Bybit by North Korean hackers.

Bybit has already paid more than $4 million to bounty hunters who helped trace and freeze some of the stolen funds.

Bybit, one of the world’s largest cryptocurrency exchanges, experienced a hack Friday in which over $1.4 billion worth of crypto was stolen, according to blockchain-analytics firms. It’s the latest incident for an industry struggling with security concerns that present hurdles to mainstream adoption.