The prosecutors in the Aaron Hernandez case are hoping to interview the tattoo artists behind tattoos the former New England Patriots tight end got last year. Hernandez has been charged with the 2013 murder of Odin Lloyd and was charged last month in the killing of two men in Boston in 2012.

Suffolk District Attorney Daniel F. Conley’s office released a statement on Wednesday, calling out for the artist or artists “who provided Hernandez with specific tattoos on his right forearm between February 2012 and June 2013,” reports The Boston Globe. Prosecutors believe that the artists may be able to provide evidence to help their case.

The statement comes a week after Hernandez was charged with two murder counts in connection with the killings of Daniel Abreu and Safiro Furtado on July 16, 2012 in Boston. Hernandez was previously charged in the murder of Lloyd, which took place on June 17, 2013 in North Attleborough.

Conley’s office did not describe which specific tattoos they are seeking information on, fearing that it might compromise anything the artists would tell them. They did say that the artists would not be suspects, but witnesses who “may have made observations of evidentiary value,” notes The Associated Press.

Prosecutors are willing to speak with anyone who gave Hernandez a tattoo during the period mentioned in the statement. However, they did mention areas where Hernandez may have gotten the tattoos in question - Massachusetts; Rhode Island; Hermosa Beach, California; Bristol, Connecticut; Palm Beach and Miami, Florida.