Muslim Leaders Sought to Negotiate Accused Bomber's Peaceful Surrender

April 23, 2013— -- In the middle of Friday night's tense standoff between federal agents and accused Boston Marathon bomber Dzhokhar Tsarnaev, leaders of the local mosque where the brothers had worshipped reached out to the FBI with an offer to try and negotiate his peaceful surrender.

"We said to the FBI, listen if you want someone to negotiate with the younger brother..." Yusufi Vali, the spokesperson for the Islamic Society of Boston in Cambridge, Mass., told ABC News. "We said we are willing to send in someone because he may have been a Muslim -- to talk to him and negotiate that process and the FBI was so grateful for that."

The standoff ended before leaders of the mosque could intervene. But during a week bookended by terror plots, the effort was one of several instances where members of the Muslim community sought to assist authorities as they confronted plots by radicals.

In Canada Monday, authorities said they were tipped off by members of the Muslim community about a plot by two men with ties to al Qaeda to derail passenger trains. In Cambridge, it was the leadership of the mosque that initially tried to confront Tamerlan Tsarnaev about his extremist views, . And later, they tried to help the FBI end its standoff with the younger Dzhokhar without more bloodshed.

The FBI didn't immediately get back to them and they didn't end up being in the negotiations that led to his capture, but Vali said the FBI did thank them for the offer.

The brothers were not formal members of the Cambridge mosque, but Tamerlan did attend prayers intermittently on Fridays as well as occasionally attending daily prayers, according to the mosque. Dzhokhar attended less frequently, but would occasionally visit to pray. Tamerlan's wife, a convert to Islam Katherine Russell, did not attend the mosque and was not known to any members, Vali said.

In recent months, Tamerlan Tsarnaev's growing radicalism led him to disrupt services, and prompted leaders of the mosque to intervene.

On November 16, 2012 a preacher at the Islamic Society of Boston gave a sermon telling the congregants it was just as appropriate to celebrate Thanksgiving, which was coming up, and July 4th as the Prophet Mohammed's birthday. Tsarnaev interrupted the service with an outburst saying the celebration of national holidays was not allowed in the Muslim faith.

On January 18th, 2013 one of the preachers said, "Martin Luther King is a great man, he is always going to be remembered as a great man," also while discussing the Prophet Mohammed. The elder Tsarnaev brother again stood up and challenged the preacher, but this time actually calling the preacher a "non-believer" and a "hypocrite."

"At which point the congregation and the people of the congregation started shouting at him, 'You need to leave!,' Vali said, recounting the incidents. "Which just kind of shows you how--both of these incidents show how the mosque really teaches an American Islam and how people inside the congregation believe in that and want to protect that."

Vali says Tsarnaev left, but afterwards the leaders of the mosque sat down with him and told him he had a "clear choice."

"Either you are silent from now on during the sermons...or you're not going to be welcome here," Vali recounted, noting there were no other outbursts or disruptions.