Their cases were heard separately, but both Anna Lucille Richter and Ashleigh Lynn Shade pleaded guilty Monday in federal court to conspiracy to distribute 100 grams or more of heroin. Afterward, however, Richter, 20, of Virginia Run, was allowed to remain free on bond; Shade, 19, of Fairfax, was taken into custody.

Federal authorities contend that, from June 2007 to mid-November 2008, they were involved in a large, heroin-distribution ring in Centreville, along with at least a dozen other young men and women. Six of them have now pleaded guilty in court and are awaiting sentencing. Court dates for the others have not yet been set.

After 19-year-old Alicia Lannes of Centreville’s Country Club Manor died in March 2008 of a heroin overdose, both local and federal authorities launched a full-scale investigation. In November, authorities charged 10 people — almost all from Centreville — with conspiracy to distribute heroin.

They arrested three more in December and, on Monday, Jan. 12, they also charged Matthew Greenlee, 23, of the City of Fairfax, with distributing heroin leading to the Sept. 7 death of Carmen Somers, 20, of Falls Church. According to the affidavit unsealed Monday in federal court, Greenlee allegedly gave her the drug and she took it at his home, the night of Sept. 6.

His arrest brings to 14 the number of people authorities say were involved in the heroin ring. And now, one by one, their cases are making their way through U.S. District Court in Alexandria.

On Dec. 9, in federal court, Centreville’s Joshua "J.R." Quick and Daniel Nash, both 19, pleaded guilty to distributing the heroin that caused Lannes’ death and are both facing sentences of as much as 20 years to life. They and Centreville residents Lokesh Rawat, 19, and David Schreider, 20, also pleaded guilty to conspiracy to distribute 100 grams or more of heroin. Rawat and Schreider could receive anywhere from five to 40 years in prison.

Virginia Run’s Skylar Schnippel, Lannes’s boyfriend, is also charged with giving her the heroin that caused her death. He’s slated for possible, grand-jury indictment on Feb. 13, unless he enters a plea before then.

Also charged with heroin dealing here are Centreville’s Tayler Leigh Gibson, Kevin Zuiker, Angela Aycock and Andrew Kacvinsky, plus Jessica Remington of Fairfax and Antonio Harper, but their cases have not yet come to court for trial or plea.

BUT MONDAY AFTERNOON, Jan. 12 — before Lannes’s parents and their own families — Shade and Richter each pleaded guilty as charged. In response to questions from U.S. District Court Judge Leonie Brinkema, Shade said she’s under the care of a psychologist and a psychiatrist, and Richter said she’s seeing two therapists for her drug addiction.

Both women waived possible indictment by a grand jury, are now legally bound by their individual plea agreements and won’t be able to change their minds and appeal their convictions or sentences. Brinkema said Shade’s agreement was 14 pages long, and Richter’s, 13.

With defense attorney Mark Miller by her side, Shade pleaded guilty to "unlawfully, knowingly and intentionally" conspiring to distribute 100 grams or more of heroin between March and July 2008.

"Do you understand that, for this offense, there’s a mandatory minimum term of five years’ incarceration and a maximum term of 40 years?" asked Brinkema. "Yes," replied Shade. Brinkema also said the court could impose a fine of up to $2 million, besides the automatic, $100 special assessment for the Victims’ Compensation Fund.

The judge said the same things to Richter and told both women they’re each likely to receive at least four years supervised probation after they’re released from incarceration. And if part of their sentence is suspended, Brinkema told each one, "The key fact you need to understand is that, if you violate any condition of your supervised release, the court could revoke any amount of your time suspended."

Brinkema said Shade’s plea agreement contained a "safety valve" clause, meaning that — with good conduct — she might receive less than five years in prison. Assistant U.S. Attorney Daniel Grooms said Richter’s agreement didn’t contain this clause because it hadn’t yet been determined whether she was eligible for it.

"You’ve agreed that you were either personally involved in the distribution of — or that it was reasonably foreseeable to you that others in the conspiracy distributed — 100-400 grams of heroin," said Brinkema to Shade. In Richter’s case, said the judge, this amount was 400-700 grams of heroin.

She told both women that, in exchange for their guilty pleas, the court agreed not to prosecute them further in the Eastern District of Virginia in connection with anything contained in their plea agreements or statements of facts. However, she added, "If you were going into Maryland or the District of Columbia to obtain drugs, those jurisdictions could still prosecute you."

BRINKEMA ALSO read aloud pertinent passages from the statement of facts within each woman’s plea agreement. To Shade, she said, "From the summer of 2007 through March 2008, you joined Remington and others in obtaining heroin for use by yourself and distribution to others. You obtained heroin from Joshua Quick, also known as J.R., and you both were aware that he was supplying it to others."

"From March to July 2008, after Quick was arrested, you and Remington began distributing heroin to people previously supplied by Quick," continued Brinkema. "You obtained it from Tayler Gibson and sources in Washington, D.C. How many sources of supply did you have in Washington?"

"Two or three," answered Shade.

Brinkema noted that authorities eventually seized some of the heroin, and Shade said, "Yes, we were in a car and they pulled us over." She also admitted that she and Remington distributed heroin to two people who turned out to be confidential informants, and that she both paid and received $160 for each transaction." Miller said they’d buy one more gram than they’d sell and use that gram for themselves.

The judge accepted Shade’s guilty plea, saying, "There’s more than enough evidence to find you guilty of this charge beyond a reasonable doubt." She set sentencing for April 10 and then ordered Shade taken to jail.

"This is a sad case," said Brinkema. "Last Thursday [Jan. 8], the defendant was a passenger in a vehicle she shouldn’t have been in, and the car was stopped by authorities. She wasn’t arrested, but she failed to report it. She also tested positive for the presence of opiates in her system — the results came back today."

Since Shade therefore violated the terms of her supervised release, Brinkema said she could no longer remain free and she revoked Shade’s bond. Shade waved goodbye to her family as she left for jail with the bailiff, but first, she listened to a warning from the judge.

"You’re going to have to decide what you want to do with the rest of your life," said Brinkema. "But if you continue to associate with people who use drugs, your life is going to be a disaster."

THEN IT WAS Richter’s turn, and the first part of the proceedings was similar to Shade’s, with Brinkema explaining the legal ramifications of her plea. However, the specific details of Richter’s case were different, and her heroin distribution was over a much longer period — between June 2007 and March 2008.

Noting that Richter’s statement of facts was three pages long, the judge said Richter admitted that, in fall 2007, she traveled to Baltimore on multiple occasions with several individuals, including Quick and Schreider, to purchase heroin from her source there.

"You introduced that source to Quick and Schreider, knowing they’d sell that heroin in Centreville," said Brinkema. "You received a portion of it for your personal use; how much?"

"A couple bags of heroin — about a gram," replied Richter. When Brinkema asked her how she used it, Richter said intravenously and that sometimes she’d ingest it.

Reading further from Richter’s statement of facts, the judge said that Richter and Rawat also went to Baltimore together to buy heroin for distribution and Richter’s personal use. Said Brinkema: "From December 2007 to March 11, 2008, you and another person began obtaining two to three grams of heroin per trip and traveling regularly to Baltimore to obtain it."

As with Shade, Brinkema found Richter guilty beyond a reasonable doubt. She set sentencing for March 27, but let Richter remain free until then. She said Richter had received a good report from the probation department and had no drugs in her system, so she could stay out of jail provided she cooperates in the preparation of her pre-sentencing report and reappears for court to receive her punishment.