MS 13 Mara Salvatrucha Trece. MS-13. The letter "M" is the 13th letter in the alphabet. The number 13 is superstitiously known as a number to be feared. Pretty fitting, considering the MS-13 Gang is now the most feared gang in all of America. Its violence is wreaking havoc on a growing number of cities and small communities across the country - making the MS-13 Gang "a terrorist organization right in our own backyard," according Detroit Police Sgt. Harold Rochon, an expert trainer on gangs and the author of a book titled, "Terrorists in Designer Jeans." This one-hour training broadcast will cover everything you need to know about the MS-13 Gang, from its origin to its identifiers - such as graffiti, tattoos, gang hand-signs and gang colors, to its method of recruiting, drug dealing, and plotting violent crimes.MS 13 Mara Salvatrucha Trece. MS-13. The letter "M" is the 13th letter in the alphabet. The number 13 is superstitiously known as a number to be feared. Pretty fitting, considering the MS-13 Gang is now the most feared gang in all of America. Its violence is wreaking havoc on a growing number of cities and small communities across the country - making the MS-13 Gang "a terrorist organization right in our own backyard," according Detroit Police Sgt. Harold Rochon, an expert trainer on gangs and the author of a book titled, "Terrorists in Designer Jeans." This one-hour training broadcast will cover everything you need to know about the MS-13 Gang, from its origin to its identifiers - such as graffiti, tattoos, gang hand-signs and gang colors, to its method of recruiting, drug dealing, and plotting violent crimes.