Jane Flavell Collins/Associated Press photo

In this courtroom sketch, Khairullozhon Matanov appeared in federal court before a magistrate judge.

facebook

An undated photo of Khairullozhon Matanov.

Facebook

Matanov was arrested by federal authorities.

Wendy Maeda/Globe Staff

Khairullozhon Matanov, 23, lived at an apartment complex in Quincy.

Wendy Maeda/Globe Staff

Ahmed Goutay said he knew Khairullozhon Matano from the Islamic Center of New England mosque in Quincy, where both studied.

Wendy Maeda/Globe Staff

Matanov frequently waited for fares outside Braintree MBTA station.

Wendy Maeda/Globe Staff

Cabdriver Bill Walker said he frequently chatted with fellow driver, Khairullozhon Matanov, outside Braintree MBTA station.

Wendy Maeda/Globe Staff

The Quincy cabdriver was a friend of slain Marathon bombing suspect Tamerlan Tsarnaev.

Reuters/File

Matanov allegedly talked to Tamerlan 42 minutes after the Marathon attack.

Wendy Maeda/Globe Staff

Resident Tyler Young, 27, said he was stunned by the accusations. “It’s shocking,” he said.

Wendy Maeda/Globe Staff

The front door of the apartment on Common Street where Matanov lived.

Wendy Maeda/Globe Staff

Neighbor Leslie Aiello, 49, said Matanov was a mysterious figure who never said hello.