MARSHALL COUNTY, MS (abc24.com) - Rico Fleming is charged with the drive-by shooting death of 16-year-old Derica Patterson of Memphis. It happened in Marshall County, Mississippi early Christmas morning. The sheriff's department is now teaming with the federal government to move the investigation along.
Detectives are joining forces with the Bureau of Alcohol, Tobacco, Firearms and Explosives. The federal agency has the nation's best resources for investigating gun crimes.
Marshall County investigators have collected all their evidence, and are concentrating on building the case against the men charged with the teen's murder.
"It's just a basic criminal investigation case, we're trying to finalize every bit of it," says Major Kelly McMillen.
Rico Fleming and Corey Albright sit in Marshall County jail. In the meantime, prosecutors are waiting to present their case to the grand jury in June.
This week the department is sending key evidence to the ATF, a law enforcement agency in the U.S. Department of Justice.
"They're going to analyze it," McMillen tells abc24.com.
The evidence includes shell casings and parts of the bullets taken from the scene and from Patterson's body.
"The projectile is the lead part that comes out of the end of the shell casing," he explains. "They're going to try to narrow that down and tell us if it came from the shell casings we collected on scene."
Deputies believe the shooters fired automatic weapons, possibly AK-47 assault rifles.
They'll use the ATF's findings to building the forensics case. McMillen expects it to be an important piece of the puzzle when it comes time to take the case to court.
A third suspect, 16-year-old Christopher Collins died last week in an ATV crash. Collins was free from jail because he was a juvenile and there was no place to hold him before trial.