A U.S. court has sentenced a South African pilot who testified against his former associate and jailed Russian arms dealer Viktor Bout to five years in jail, a RIA Novosti correspondent reported.

Andrew Smulian, 71, who also holds British citizenship, was arrested in 2008 in Thailand along with Bout in a sting operation in which U.S. agents posed as Colombian militants looking to buy weapons.

Bout, a former Soviet Air Force officer who was dubbed the “Merchant of Death” in the United States, has been sentenced to 25 years in a U.S. jail for conspiring to kill U.S. citizens and sell arms to the Colombian militants. He maintains his innocence.

Announcing Smulian’s verdict on Wednesday, Manhattan federal court Judge Shira Scheindlin, who also presided over Bout’s trial, said he could be freed in a few months since he had already spent more than four years in detention.

Upon his arrest, Smulian agreed to cooperate with U.S. investigators and testified against Bout in his trial last fall.

Smulian has been allowed to serve his sentence at a pretrial detention centre in Manhattan where he has been jailed for the past 50 months.

Earlier this month, the U.S. penitentiary authority said Bout would be sent from his Brooklyn jail to a super maximum security prison in Colorado, where convicted terrorists and other dangerous criminals are serving their sentences, often in solitary confinement.

Bout’s lawyer, Albert Dayan, has already appealed to the court, asking to revoke its decision.