Anzor and Zubeidat Tsarnaev, who spent 12 years in the Boston area, are living in the Russian republic of Dagestan and generally avoiding the news media. A reporter for Britain's Channel 4 News said he spent two days with the couple.
Tamerlan and Dzhokhar Tsarnaev, who remained in the United States when their parents left, allegedly set off two bombs near the Marathon finish line April 15, killing three people and injuring more than 160.
Tamerlan, 26, was killed during the hunt for the bombers, and his 18-year-old brother is in jail.
"I loved the USA. I really did," Anzor Tsarnaev said. "I loved the USA. Until it killed my son."
Police say Tamerlan was wounded in a shootout and then killed when his brother ran him over as he tried to drive away. But their parents do not accept that.
Anzor Tsarnaev displayed a photograph of his son's body in the morgue.
"Look at what they did to my son! They must have cut and hacked him, then hung him upside down," he said. "Look at the blood that's run to his neck and head."
Zubeidat played a recording of a conversation she and her husband had with Dzhokhar after his arrest.
"I thought he was going to scream, what's going on? He would ask the world, what's going on?" Zubeidat said. "But instead he was just calming me down, he was trying to calm me down. Mama, you don't worry about anything. I hope you're not getting any problems. Are you OK there? Everything is going to be OK, Mama, I eat, they give me already rice, and I started eating chicken. So he was trying to make us calm, you know?"