In the wake of the Marathon bombings, Middlesex County began to probe a link between the elder Tsarnaev and Brendan Mess, one of the three men killed in the gruesome slaying on Sept. 11, 2011. Officials said Mess and two men were found in a Waltham residence with their throats slit and their bodies covered with marijuana. Tamerlan and Mess were once roommates and did boxing and martial arts training together.
Now law enforcement officials tell ABC News that some crime scene forensic evidence provided a match to the two Tsarnaev brothers. The officials also said records of cell phones used by the Tsarnaevs appears to put them in the area of the murders on that date. Several officials confirmed the new findings but declined to be identified because they are not authorized to comment on the ongoing investigation.