Nidal was born in the Dagestani city of Buinaksk in 1992. The Russian newspaper Novaya Gazeta first broke the story about Nidal's ties to Tamerlane, which argued that the Dagestani militant was a key contact of the elder Tsarnaev brother during his 2012 visit to the mountainous Russian republic of Dagestan. While some newspapers and Western media have incorrectly reported that Nidal is an ethnic Chechen, he is actually from Dagestan and is half ethnic Kumyk and half Palestinian. The Kumyks--the third largest ethnic group in the republic of Dagestan--are a Turkic speaking people who are of Mongol descent.
Whatever ties existed between Tamerlan and Nidal, they did not last long. Mahmud Mansur Nidal was 19 years old when he was killed in a police operation in Makhachkala on May 19, 2012. He put up his last fight at his home, located on 1b, Yubileinaya Street in Makhachkala, which the Dagestani police surrounded on the evening of May 18. Apart from Nidal, also present in the domicile were Mansur's mother, Zarina, Mansur's spouse, Maryam (a.k.a. Anzhela) Dolgatova, with their two-month-old infant, along with their guests, Fatima Nurmagomedova and her husband, Abdurakhman Magomedov.
Following many hours of negotiations, the women and children were allowed to leave the house. Abdurakhman Magomedov also surrendered to the authorities. However, Mansur Nidal refused to surrender and fought the police forces and was subsequently killed by the security services as they stormed the building.
According to Dagestani police reports, by December 2011, Mansur Nidal was accused of being a member of the Shamilkala (a.k.a. Makhachkala) Jamaat. The police suspected Nidal of participating in several killings, bomb attacks and assaults on government forces, including an attack on a police checkpoint in Makhachakala on May 3, 2012. In that specific terrorist attack, which was carried out by suicide bombers, 13 people died and over a hundred were injured. Mansur Nidal denied his involvement in this attack to the police in the midst of their siege of his home, stating that he had been out of town that day.
Unofficial sources allege that during the special operation at Nidal's home, a crowd of 150--200 young people attempted to prevent the police from storming the building. The protesters blocked the street where the police operation was taking place. This type of behavior by civilians is quite unusual for Makhachkala.
Discussions of how connection is improbable than then this conclusion:
The Moscow papers' stories about Tamerlan Tsarnaev's visit to Georgia, about his contacts with Mansur Mahmud Nidal, or even his possible contacts with the Canadian William Plotnikov are nothing more than attempts to deflect attention from what Tamerlan Tsarnaev was really doing on his last visit to Russia.