Ambrose faces trial this month in the Adkins shooting, and prosecutors plan to use those letters against him.
In the last several years, street gangs - particularly the Bloods - have been filtering down from Trenton and North Jersey, becoming an increasing presence in Camden County.
In that time, the jail's gang unit has become integral in keeping order in a crowded jail and providing intelligence to investigators on the street.
Since the unit was created in 2004, its members have originated or contributed to more than 100 criminal cases like Ambrose's. Two members of the unit are assigned to work with the Prosecutor's Office.
"They're a very useful group of people," said acting Camden County Prosecutor Joshua Ottenberg. "We can't just go knock on doors and say, 'We want to talk to you.' In jail, it's a different relationship."
At an annual awards banquet in May, the Prosecutor's Office honored the unit for its work.
The gang unit was established by Eric M. Taylor, who became the jail's warden in 2004, six years after retiring as chief of corrections in New York City, where he ran Rikers Island and 15 other facilities.
In New York, Taylor was a pioneer in recognizing the growing strength of gangs on the East Coast, and in realizing the role that jails could play in combating them.
When he arrived in Camden County, gangs weren't as prevalent as they are now. But since 2005, the unit has identified 850 gang members in the jail.
This week, gang members in the jail numbered 175.
"That's over 10 percent of your population," Taylor said.
Though the Bloods are the most prevalent, the jail also has members of the Crips, the Latin Kings and Nietas.
Jails and prisons are prime locations for gangs to recruit members and formulate their plans for the outside, making intelligence gathered from behind bars particularly valuable.
"They're more organized in the facility than they are on the streets," said Officer Wayne Norton, a member of the gang unit.
