A U.S. grand jury on Thursday indicted two students from Kazakhstan on obstruction of justice charges, alleging they helped hide evidence, related to the April Boston marathon bombing that killed three and injured 264.

Dias Kadyrbayev and Azamat Tazhayakov, both 19, were college friends of surviving bombing suspect Dzhokhar Tsarnaev.

They are charged with removing a backpack containing fireworks and a laptop from Tsarnaev’s dorm room, after the FBI released pictures of Dzhokhar and his older brother, Tamerlan, in an effort to learn the names of the bombers, the U.S. Attorney’s office for Massachusetts said.

The pair were first charged on May 1 with conspiracy and remain in federal custody. They could face up to 20 years in prison on obstruction of justice charges, in addition to five years if convicted on conspiracy charges. Both also face the possibility of deportation.

Tamerlan Tsarnaev died in a gun battle with police following the release of the images while Dzhokhar, 20, is in federal custody awaiting trial on charges that could bring the death penalty.

An attorney for Tazhayakov, Arkady Bukh, said he had been trying for the past three months to persuade federal prosecutors to drop charges against his client, stating they had no motives to destroy evidence.

The initial charges against the two Kazakh students and another criminal count, making false statements in a terrorism investigation filed against Robel Phillipos of Cambridge, Massachusetts, came weeks after the April 15 bombing.

They trace back to the evening of April 18, three days after the attack, when the FBI released still images from videos taken at the race’s crowded finish line, showing the two brothers, wearing baseball caps and carrying backpacks near the site where two homemade pressure-cooker bombs exploded.

After seeing the pictures and realizing one was their friend, the Kazakh students got in touch with Dzhokhar Tsarnaev, who told them by text message they “can go to my room and take what’s there.”

Tsarnaev made his first appearance in court last month, where he pleaded not guilty to all charges associated with the attack and its aftermath.

Phillipos’ lawyer said in a court filing on Thursday they are “engaged in negotiations aimed at a possible resolution of this matter” and a judge granted his request to waive a probable cause hearing that had been scheduled for Monday.  

— Reuters, TAAN