Dzhokhar Tsarnaev admitted to investigators under questioning Monday that he was involved in laying the bombs that killed three people and wounded scores at the finish line, The New York Times reports.
Tsarnaev, 19, said he and his brother Tamerlan, 26, hatched the plot themselves and were not tied to a terrorist group.
The older Tsarnaev was killed Friday in a shootout with police. The younger brother was apprehended that evening, wounded but alive, in Watertown, Mass.
He has been charged with conspiring to use a weapon of mass destruction against persons and property, resulting in death. He faces a possible death sentence.