Evidence about the Boston Marathon bombing suspects’ ties to Islamism and Chechen radicals deepened Thursday as multiple news outlets reported that Dzhokhar Tsarnaev claimed the attacks were made on behalf of Islam in retaliation for U.S. foreign policy.

According to law enforcement officials speaking on the condition of anonymity, suspect Dzhokhar Tsarnaev scribbled a chilling note to police on the side of the cabin of the boat in which he was hiding as police closed in: “When you attack one Muslim, you attack all Muslims.”

The writings were first reported by CBS News. Other reported phrases include “f– America” and “praise Allah.”

Tsarnaev also wrote that the bombings, which tore through the iconic event April 15, were retribution for U.S. military action in Afghanistan and Iraq, CBS reported. He said that the victims of the Boston bombings – three were killed and more than 260 wounded – were collateral damage just as many Muslims have been innocent casualties of American wars in Iraq and Afghanistan.

Tsarnaev also said that he didn’t mourn his elder brother, Tamerlan, the other suspect in the case. He called his brother a martyr in paradise and said he would join him there eventually, CBS reported.

Also Thursday, Voice of America interviewed a former Chechen fighter living in the U.S., in which the ex-guerrilla said he met three times with Tamerlan Tsarnaev since a 2006 gathering of the Chechen Society of Boston.

Musa Khadjimuradov confirmed to VOA that the FBI had searched his New Hampshire home this week and examined his computer hard drives. He denied having radicalized Tamerlan or discussed in depth Chechnya’s independence struggles from Russia, in which Islamist guerrillas have played a major role.

“Nothing, never. He never talked about the religious, politics or anything like that to me,” Mr. Khadjimuradov told VOA. “I believe that they thinking that he come here to New Hampshire and I try to help him or do something like that.”

FBI officials took samples of Mr. Khadjimuradov’s DNA and fingerprints. He came to the U.S. in 2004 and was granted asylum.