The two men suspected of orchestrating the twin bombings at the Boston Marathon may have been planning to head to New York City before the elder brother Tamerlan Tsarnaev, 26, was killed in a gunfight with police, investigators say.

That theory was corroborated by a victim who was carjacked by the Tsarnaev brothers just before the 20-hour-long manhunt that eventually led to Dzhokhar Tsarnaev’s capture, according to CBS News. The man, who hasn't been identified, reportedly told police that, while he was held hostage by the Tsarnaevs, he overheard part of their conversation. Although the hostage said that most of the conversation was conducted in Russian, he told police, “The only word I recognized was Manhattan.”

The victim, whose Mercedes-Benz was hijacked by the bombing suspects, said the Tsarnaevs bragged about their role in the Boston Marathon bombings and held him up at gunpoint until they eventually ejected him uninjured from the car in front of a Cambridge gas station. The gas station’s owner, Tarek Ahmed, later told the police that he didn’t believe the victim’s account when he ran into the station screaming for help.

"I thought he was drunk," Ahmed said. "I didn't believe him when he came in; it just sounded very crazy. He came very fast and was nervous and was afraid of the guy. He said they pushed him out of the car.”

CBS’s John Miller reported that the victim’s account “tripped a lot” of alarms for law enforcement officials, and it spurred the New York Police Department to “flip on its network of license plate readers at all bridges and tunnels coming into the city.” The report also prompted Amtrak to temporarily suspend service to and from Boston, including travel to and from Providence, R.I., and New York, as authorities probed the train line looking for Tsarnaev.

Miller added that authorities "loaded all the license plates associated with these guys" in an effort to prevent him from entering New York City.

Dzhokhar Tsarnaev, 19, who remains at Beth Israel Deaconess Hospital in Boston, where he's being treated for neck and leg wounds, was charged on Monday with use of a weapon of mass destruction and malicious destruction of property resulting in death. Miller said that Tsarnaev has told investigators that he was “driven by his brother” to participate in the crimes, and he said that “it was mostly done online, in terms of radicalization [and] finding instructions.”

White House Press Secretary Jay Carney has said that Tsarnaev won't be treated as an “enemy combatant,” but he hasn’t commented on whether or not the U.S. attorney’s office plans to seek the death penalty.