Anecdotes suggest that Mr. Tsarnaev became more religious in the last several years and may have embraced more conservative Islamic ideas. 

On Monday, a spokesman for the Islamic Society of Boston, a Cambridge mosque, said Mr. Tsarnaev disrupted a talk there in January, insulting the speaker and accusing him of deviating from Islam by comparing the Prophet Muhammad to the Rev. Dr. Martin Luther King Jr. It was the second time he had disrupted an event at the mosque because he felt that its religious message was too liberal, said the spokesman, Yusufi Vali, according to a report in The Boston Globe.