A former State Department employee has pleaded guilty in an identity theft scheme in which a key witness in the federal probe was gunned down outside a D.C. church, according to court documents and law enforcement officials.

No arrests have been made in the 2008 slaying of a co-conspirator in the scam, and D.C. police have said they have no information that the killing is connected to the identity theft scheme.

Twenty-six-year-old Rodney P. Quarles Jr., of Charlotte Hall, Md., a former low-level employee in the Department of State's Bureau of Consular Affairs, admitted in U.S. District Court of D.C. on Friday to a charge of conducting illegal transactions with credit cards. The charge carries a maximum penalty of 15 years in prison.

According to prosecutors, from September 2007 to 2008, Quarles worked in the Passport Office, where his job consisted mainly of destroying old passports and passports that had been reported lost or stolen. He got the job as a member of the department's student work program.

As part of the conspiracy,

a mail sorter for the U.S. Postal Service stole credit cards from envelopes, and the names on these cards were passed along to Quarles. Using his position at the State Department, Quarles used the agency's database to retrieve personal information to activate the credit card accounts.

Quarles accessed the files of least 700 people, court papers said. The identity theft ring stole credit cards and used them to obtain about $72,000 worth of in ATM withdrawals, jewelry, electronics, gift cards and designer clothing.

But the scheme unraveled in March 2008 during a routine traffic stop of one of the conspirators, a 24-year-old with the unusual name of Lieutenant Quarles Harris Jr.

D.C. police searched Harris' vehicle and found more than dozen ziplock bags containing marijuana.

He arrested possession with intent to distribute. During a search of Harris, police found 19 credit cards and eight passport application printouts.

Harris revealed that his connections in the State Department and postal service.

He agreed to cooperate with federal investigators to tell a grand jury what he knew.

On April 17, 2008, police responding to the sound of gunshots and found Harris slumped dead over the steering wheel of his car in front of the Judah House Praise Baptist Church in Northeast D.C.