The nearly two-year-old federal investigation into allegations that cycling legend Lance Armstrong used and distributed performance-enhancing drugs came to an abrupt end Friday when the office leading the multitiered probe announced it was shutting it down.

Though Armstrong had vehemently denied the charges, his legacy as a seven-time Tour de France champion and cancer spokesman seemed under siege as the U.S. Attorney’s Office in Los Angeles opened a grand jury investigation in the summer of 2010 and summoned former teammates, friends and associates of Armstrong to testify.

“I am gratified to learn that the U.S. attorney’s office is closing its investigation,” Armstrong said in a statement. “It is the right decision and I commend them for reaching it. I look forward to continuing my life as a father, a competitor, and an advocate in the fight against cancer without this distraction.”

In the unusual announcement, U.S. Attorney André Birotte Jr. said Armstrong and his former professional cycling teammates would not face federal charges. All elements of the investigation that included the U.S. Food and Drug Administration, the FBI and the U.S. Postal Service Office of the Inspector General have ended.

“The United States Attorney determined that a public announcement concerning the closing of the investigation was warranted by numerous reports about the investigation in media outlets around the world,” the office said in a statement.

The decision might have been influenced by the recent decision in the highly publicized federal case against Barry Bonds, who was found guilty of obstruction of justice last year but avoided a jail term because he avoided conviction on charges of lying about using steroids. A mistrial was declared last July in the perjury case against Roger Clemens, who has been accused of lying to Congress about performance-enhancing drug use. A retrial is scheduled for April 17.

The case against Armstrong began after Floyd Landis, a former teammate, publicly accused him of using drugs and supplying them to other cyclists. A second teammate, Tyler Hamilton, made similar charges last year during an interview on the news program “60 Minutes.”

Armstrong is believed to have spent millions in preparing to defend himself against possible federal charges. He hired publicist Mark Fabiani, who represented President Bill Clinton during the Whitewater scandal, and a high-powered legal team including San Francisco-based Elliot Peters and John Keker, who prosecuted Oliver North in the Iran-Contra affair.

The U.S. Anti-Doping Agency, which also has been investigating doping allegations against Armstrong and professional cycling, released a statement Friday saying its probe would remain open.

“Unlike the U.S. Attorney, USADA’s job is to protect clean sport rather than enforce specific criminal laws,” USADA chief executive Travis Tygart said. “Our investigation into doping in the sport of cycling is continuing and we look forward to obtaining the information developed during the federal investigation.”

It is unclear whether federal investigators will hand over material obtained in the case, though there is some precedent for doing so. A spokesman in the Los Angeles office declined to comment.

Federal grand jury secrecy laws would seemingly exempt any information gathered by the grand jury investigation, but before the 2004 Summer Games in Athens, federal investigators turned over information gathered in the doping probe known as Balco to USADA to attempt to ensure that the United States sent a clean team to the Summer Games.