Updated

Boston Marathon bombing suspects Tamerlan and Dzhokhar Tsarnaev befriended a brain-damaged anti-U.S. government conspiracy theorist through their mother's health care aide job years before the deadly attack, a lawyer said Tuesday.

Attorney Jason Rosenberg, who represents the family of Donald Larking, said Larking shared publications with the brothers and discussed theories including that the Sept. 11, 2001, terror attacks and the Newtown, Conn., elementary school shooting didn't happen or the U.S. government was behind them.

The attorney said the Tsarnaev family had a relationship with the Larkings that started years ago when the brothers' mother began working as a personal care assistant for Larking's wife, a quadriplegic since birth.

Rosenberg said Larking, who lives in West Newton, just west of Boston, was shot in the head in 1974 in an attempted robbery while working in a convenience store. He said Larking suffered brain damage that led to problems with his decision-making and judgment.

Authorities say the Tsarnaev brothers orchestrated the April 15 marathon bombing, in which two pressure cookers loaded with shrapnel exploded near the finish line, killing three people and injuring more than 260 others. Dzhokhar Tsarnaev pleaded not guilty last month to charges including using a weapon of mass destruction to kill. Tamerlan Tsarnaev died after a shootout with police a few days after the bombing.

Rosenberg said Tuesday the Tsarnaev brothers got to know Larking while substituting for their mother sometimes by helping to care for his wife. The attorney said the brothers "helpful" and "kind" to the couple and Larking shared his views with them as he found anti-U.S. government websites and became angrier and irrational.

The lawyer's account first emerged in a Wall Street Journal article, which included Tamerlan Tsarnaev's former landlady talking about publications that had been in his Cambridge apartment.

Landlady Joanna Herlihy told The Associated Press she salvaged publications after authorities had searched the apartment and items were discarded. She confirmed that among them were an Alabama-based publication that uses a Confederate flag on its website and a weekly publication that the Southern Poverty Law Center calls anti-Semitic.

Rosenberg said Tuesday he doesn't think Larking helped the Tsarnaev brothers, ethnic Chechens from Russia, formulate ideas but may have made them believe others felt as they did.

"(They) were seeing someone who was Caucasian and was born in America who was saying the same things," the attorney said.

Rosenberg said he doesn't know if the Tsarnaev brothers understood how seriously Larking's brain was affected from the long-ago shooting. He said he's talked to Larking since the Boston Marathon bombing but doesn't think his friend comprehends what happened.

The brothers took Larking to their mosque, and he converted to Islam and still attends the mosque, Rosenberg said.

Larking seemed close to Tamerlan, and Tamerlan made sure to help Larking, who wears braces on his legs, when they attended the mosque together, said Nicole Mossalam, a spokeswoman for the Islamic Society of Boston mosque in Cambridge.

Mossalam said it becomes obvious during conversation that Larking has a disability because he's unusually open and "childlike" and often says politically incorrect things without seeming to realize it.

"He loves to sit down with people and talk, and there's basically no filter," she said.

In a federal indictment in June, authorities alleged they found on Dzhokhar Tsarnaev's computer a publication written by someone known as the Father of Global Jihad that advocates violence to terrorize Islam's perceived enemies.

Prosecutors also alleged he downloaded a publication that "glorifies martyrdom in the service of violent jihad" and an Al Qaeda magazine that had directions for building bombs using pressure cookers.