Before the young mother dubbed the “blonde bandit” was arrested in a series of carjackings and bank robberies last fall, she was a player in a large heroin ring that moved “bricks” of the drug from New York to Virginia, court documents show.

The new details emerged as Stephanie Schwab, 26, who grew up in Manassas, pleaded guilty Thursday to charges related to her high-profile crime spree and the drug conspiracy as part of a deal with federal prosecutors in Virginia.

Schwab could be sentenced to up to 70 years in prison. She admitted she committed a carjacking, robbed two banks and attempted to rob a third in November, and was part of a group that distributed more than 700 grams of heroin across the Washington area, according to court documents.

Alfred Robertson Jr., Schwab’s attorney, said a growing heroin addiction led her to commit the 13-day string of crimes in Northern Virginia and Maryland that transfixed the region and made her a fixture of the nightly news.

“Stephanie is going to pay the price for not making the right decision,” Robertson said. “She knows she has to pay a debt and wants to pay that debt. She doesn’t want to see anybody else hurt.”

Stephanie Schwab. (The Associated Press)

The plea deal leaves open the possibility that Schwab could face additional charges in Maryland or be called on to testify against other alleged members of the heroin ring — a role she has played before.

In 2005, Schwab, a former member of the Mara Salvatrucha, or MS-13, testified against gang members accused of killing a fellow 17-year-old gang member, who had become a government informant. Schwab was placed in a federal witness protection program but eventually left, family members said.

Schwab began working with the heroin ring in 2009, according to court records. She traveled to New York, the District and Maryland to buy heroin and then sold it in the Manassas area, court records show.

In court, Schwab gave brief answers to a judge’s questions about her crimes. She also said she had been twice treated for heroin addiction and had received a diagnosis of bipolar disorder.

The plea deal revealed new details about her spree. It began when Schwab stole a Chrysler Town & Country that was parked at a relative’s Fauquier County house and drove it to rob a Virginia Commerce Bank in Manassas the next day, court records show.

Schwab gave a teller a note that said “Gun Cash $10,000” and made off with $1,368, according to court records. After that robbery, the crimes came quickly.

On Nov. 19, she carjacked a woman at knifepoint at Tysons Galleria and then went to rob a West Springfield BB&T bank of $1,830, according to court papers. She gave the teller with a note that read “I have a gun give me the cash now.”

Schwab is also accused of stealing a Ford Escape from a woman in Baltimore County on Nov. 30. She admitted that that day she went to rob a McLean bank but fled without any money after the teller pushed a silent alarm, court records show.

As she drove away, Schwab was tailed by a Fairfax County police officer who followed her to Montgomery County, according to court records. Schwab swerved into oncoming traffic, causing a three-car crash. She dashed away from the Ford and was caught.

Schwab pleaded guilty to bank robbery, transporting a stolen vehicle across state lines and conspiracy to distribute heroin.

“Stephanie Schwab learned the hard way that crime doesn’t pay,” said Neil H. MacBride, U.S. Attorney for the Eastern District of Virginia. “Today, she took responsibility for the terror she instilled in bank employees and residents throughout the D.C. metro area.”