A mail carrier used her daily route to move cocaine shipments in falsely addressed packages on behalf of a drug trafficking organization based in Puerto Rico, federal authorities said Tuesday.

The U.S. attorney's office in New Jersey said Christina Nunez has admitted receiving packages of cocaine from Puerto Rico and passing them to a co-conspirator in Camden.

Nunez, her hair in French braids and wearing prison scrubs, was appointed a public defender Tuesday during her initial appearance in a Newark federal courtroom. She didn't enter a plea. She later was released on $100,000 bail and is subject to electronic monitoring.

Prosecutors say Nunez, who was assigned to a post office in Secaucus, was responsible for moving more than 18 kilograms of cocaine from October 2010 until her arrest on Aug. 24. The 30-year-old from Lyndhurst is charged with conspiracy with intent to distribute cocaine and mail theft. A spokesman for the U.S. Postal Service said her employment status following her arrest was not immediately known.

Her boyfriend also has been arrested and charged.

A spokesman for the U.S. attorney's office said the approximate street value of the drugs wasn't immediately available.

Federal authorities were alerted to the scheme after postal inspectors in February 2011 seized an Express Mail package containing cocaine that had been addressed to a location along Nunez's route, according to a criminal complaint.

Investigators then found that packages with similar weights and sequential tracking numbers but bearing false or inaccurate addresses had been sent along Nunez's route dating back to October 2010, according to court papers. Prosecutors said Nunez switched to receiving packages at her Lyndhurst residence while out on medical leave or to her boyfriend's former addresses.

Authorities then found a package destined for Nunez's route that contained cocaine concealed in a bag of coffee, court papers said. Investigators replaced the drugs with a false substance, inserted a GPS tracking device into the package and began conducting surveillance of Nunez along her route and monitoring the inside of her mail truck via video.

Nunez failed to deliver the package containing the GPS device, according to the complaint, and instead returned home with it.

The complaint said Nunez and her boyfriend admitted after their arrests that Nunez had been receiving packages addressed to her route that she knew contained controlled substances from a drug trafficking organization in Puerto Rico.

Prosecutors say Nunez has admitted intercepting the packages, scanning them as delivered and then sending them instead to a co-conspirator in Camden in exchange for $500 to $600 per package, according to the complaint.