A violent gang member shot and killed a 50-year-old man who was trying to protect his son after a dispute in an Indiana gas station parking lot, but the shooter ended up getting caught when witnesses told detectives he had a cross tattooed on his face and drove a green and red Mercury, federal prosecutors say in new court papers.

Manuel Diaz, 26, who prosecutors say is a member of the Latin Dragons gang, got into a dispute in the parking lot of Luke’s Gas Station in East Chicago, Indiana, on September 30 after a passenger in his car flashed gang signs at another man who responded by flashing a handgun. Diaz followed the man who showed the gun and fired one shot from his car that hit the man’s father, Charles Berrios, 50, court papers state.

When police arrived at the scene, they found “Berrios laying in the driver’s seat unresponsive but breathing from an apparent gunshot wound to the right side of the head,” according to court papers. Berrios was airlifted to a Chicago hospital but didn’t survive.

After witnesses told detectives the shooter was a Hispanic man in his 20s with a small tattoo of a cross under his left eye who was driving a green Mercury Cougar with a red bumper, local police looked out for that vehicle and pulled it over the next day. Diaz was driving and was arrested after police found marijuana in his car, and while he denied shooting at another car the previous day, investigators noticed the cross inked under his left eye, according to court papers.

Also on October 1, a passenger in Diaz’s car told investigators that after the gas station dispute, Diaz had pulled a silver revolver from under his seat and fired a single shot at Berrios’s car. “Diaz then placed the revolve on his lap and drove away from the area,” the court papers state. “Diaz eventually placed the silver revolver under the driver’s seat.”

Diaz was charged with murder in aid of racketeering, federal prosecutors announced Wednesday. (Court records didn't list a defense attorney for Diaz.) The charges come as the Latin Dragons —who sell marijuana and cocaine and have been involved in multiple murders in Chicago and Northwest Indiana— have been trying to enlarge their territory in Northwest Indiana towns like East Chicago, according to court papers.

“These concerted efforts have focused in part on taking advantage of the void left by recent federal indictments of the Latin Kings, Imperial Gangsters and Two Six street gangs in the Northern District of Indiana,” the complaint against Diaz states. The month before Berrios was shot, East Chicago cops found a large gang mural of the word "DRAGONS" with the signs of other gangs painted upside down in a show of disrespect.