Police Officer Kirsix De La Cruz needed money for a class to prepare for the sergeant’s exam last summer, so prosecutors say she asked her uncle for a few thousand dollars. She allegedly wound up repaying the uncle by helping him rob a drug dealer.

Federal prosecutors say Ms. De La Cruz, 33, introduced her uncle to a drug dealer who knew where other dealers kept their drug stashes. The uncle was arrested last July and has been cooperating with an FBI investigation of his niece. His name was not released.

Ms. De La Cruz’s alleged downward spiral into the criminal world stemmed from her efforts to move up the law-enforcement ladder after 10 years with the New York Police Department. Prosecutors say she needed money to take a preparatory course for the $60 sergeants’ exam. The courses cost about $1,500.

Ms. De La Cruz and two other drug dealers who conspired with her uncle to rob a stash house, Luis “Pedro” German and Markus “White Grande”Vizaniaris, will be arraigned on various drug and conspiracy charges next week for the theft of seven kilograms of cocaine last July. The government is seeking $5 million from Ms. De La Cruz and the two other defendants – the street value of the cocaine that was allegedly stolen but never actually sold.

Ms. De La Cruz was known as Kristi at the 33rd Precinct in Washington Heights, where she worked in computer operations until last month, when she was arrested and resigned.

According to the federal complaint against her, Ms. De La Cruz seemed acutely aware of her wrongdoings and complained at one point in the conspiracy that she had “more to lose than everybody.”

Prosecutors say Ms. De La Cruz borrowed the money in the first few days of July 2005. Her uncle then allegedly asked her to set up a meeting with others who would participate in his robbery scheme. On July 9, prosecutors say, Ms. De La Cruz arranged for her uncle to meet Mr. German.

Within days, the uncle made good on the introduction, assembling a band that included Mr. German and two others he knew previously: Mr. Vizaniaris and another individual whom the uncle did not know was a government informant. The uncle’s scheme involved him posing as an undercover police officer during a raid of the stash house, and he apparently believed the informant’s role was to sell the drugs.

Prosecutors say the uncle and Mr. German initially planned to rob a stash house on West 100th Street that contained between $300,000 and $400,000 in cash on July 11. They canceled the heist at the last minute when they suspected someone was on to them.

On July 13, however, they allegedly entered a Washington Heights stash house and stole seven one-kilogram bricks of cocaine. The uncle allegedly paid Mr. German with one of the bricks, and subsequently called Ms. De La Cruz to share his success and arrange payment. She told him she preferred to be paid in “the green,” or in cash, according to prosecutors.

Later that day, the uncle was arrested and police confiscated his backpack, which contained six kilograms of cocaine, and a loaded gun. Prosecutors say he subsequently cooperated with government investigators, and on January 27 began helping them build a case against Ms. De La Cruz.

According to prosecutors, the uncle implicated Ms. De La Cruz by persuading her to check an NYPD database of offenders and access the records of Messrs. German and Vizaniaris under the guise of protecting them both against information the two could have told police about the robbery. Investigators were recording those calls under agreement with the uncle.