BRUSSELS (AP) — A court has acquitted for lack of evidence 18 suspects accused of being involved in a massive 2013 diamond heist at Brussels Airport when tens of millions worth of gems were stolen from the hold of a departing Swiss-bound plane.

One other person, suspected of being the mastermind, will hear his case in court later.

Defense lawyer Nathalie Gallant said the "acquittal is the proof that prosecution failed to bring evidence on the involvement of each of the accused, and there were a lot of them."

The heist was estimated at $50 million at the time and was one of the biggest of recent times. It stunned the world with its clockwork precision of breaking into the high-security airport runway, driving up to the plane and, flashing guns, grabbing the diamonds.