BOGOTA (Reuters) - The nephew of a former commander from Colombia’s FARC rebels has traveled to the United States to testify to U.S. authorities about a plot to sell 10 tonnes of cocaine to Mexico’s Sinaloa cartel, Colombian law enforcement sources said on Tuesday.

Marlon Marin, 39, the nephew of former Revolutionary Armed Forces of Colombia (FARC) rebel commander and soon-to-be senator Luciano Marin, was arrested in Colombia last week with another former rebel leader, Seusis Hernandez, and two others.

The cocaine would have an estimated street value of $320 million in the United States, Colombia’s attorney general said at the time of the arrests.

Hernandez, known by his nom de guerre Jesus Santrich, Marin and the others were indicted by a grand jury in the Southern District of New York for drug trafficking. Hernandez is in custody in Colombia awaiting extradition to the United States.

The U.S. Justice Department declined to comment.

A source at the attorney general’s office told Reuters that there was no request for Marin to be extradited to the United States, but, “after being released, he contacted the (U.S. Drug Enforcement Administration) and traveled in the last few hours to the United States.”

A Colombian police source told Reuters that Marin would inform on the trafficking network and Hernandez’s role in it in exchange for judicial benefits.

The FARC has said the accusations against Hernandez are false and that his arrest puts the peace process in danger.

Hernandez and Luciano Marin, known by his nom de guerre Ivan Marquez, are both slated by the FARC, now a political party, to take up seats in Congress in July.

Under the terms of a 2016 peace deal with the government, the FARC handed over thousands of weapons and pledged to abandon drug trafficking, which had been a key source of financing for the group during five decades of war, in exchange for 10 guaranteed seats in Congress through 2026 and other benefits.

Crimes committed by FARC members during the war are to be adjudicated by a special tribunal, but those committed after demobilization are subject to regular judicial procedure, which includes the possibility of extradition. The government has said that Hernandez’s alleged crimes took place after the deal was signed.