What is clear is that it will be some time before the probe ends and a decision is made.
One of Armstrong's former teammates, Floyd Landis, made headlines last May when he accused Armstrong of cheating to win - using performance-enhancing drugs and teaching others how to beat drug testing. Speculation ran rampant that criminal charges soon would follow. They didn't.
A grand jury investigation based in Los Angeles appeared to be moving fast last summer. Then the published reports emerged. The new year and the Super Bowl, both reported target dates for a decision, came and went without charges.
In fact, the nine months since Landis made his allegations have only served to illustrate the difficulty of translating them into legal charges.
Armstrong has never been found to have failed a drug test and there is a dispute over whether any forensic evidence exists that could be used against him. So far, Landis, whose credibility is open to question, is the only person to say publicly he saw Armstrong doping. Whether investigators have found other eyewitnesses among current or former Armstrong associates remains unclear.
Investigators have many more witnesses to interview, and the assistant U.S. attorney supervising the investigation, Doug Miller, is set to handle an unrelated criminal case, according to lawyers familiar with the investigation.
The reports of an impending indictment led Armstrong's lawyers to reach out to the U.S. attorney's office in Los Angeles. Over the past month and a half, that office has assured Armstrong's legal team that no decision on whether to indict is imminent, according to the lawyers. They spoke on condition of anonymity because the criminal probe is continuing.
In line with Justice Department policy, Armstrong's lawyers will get time to argue privately against indictment if the government decides to move toward charging their client, three of the lawyers said.
The only certainty is that it will be quite a while before the Armstrong probe ends.
Thom Mrozak, a spokesman for the U.S. attorney's office in Los Angeles, and Mark Fabiani, a spokesman for Armstrong, declined comment.
ARMSTRONG, BARRY BONDS AND ROGER CLEMENS
The lead investigator in the Armstrong probe, Jeff Novitzky, was instrumental in getting federal criminal charges filed against baseball home run king Barry Bonds and seven-time Cy Young award winner Roger Clemens related to their alleged involvement with performance-enhancing drugs.
The Bonds trial is to begin in March; Clemens' case in July.
Armstrong, 39, stands near the end of a storied career, just as Bonds and Clemens did when they became the focus of investigations into steroid use.
But there's one major difference: The probe of Armstrong seems to lack a defining event, the kind that led to charges against Bonds, who is accused of lying to a federal grand jury, or Clemens, who allegedly lied to a congressional committee in a nationally televised hearing.
Armstrong, if anything, has been even more vehement than Clemens and Bonds in denying he engaged in doping.
Plagued by a long history of abuse, the cycling world imposed drug testing long before major league baseball tightened its rules and tests. So Armstrong has been tested hundreds of times over the years for banned substances. He has never been found in violation.
In their hunt for a violation of law, investigators have covered a lot of old ground in Armstrong's life. Among the questions they have asked: Did Armstrong lie about drug use in a civil suit in a Texas state court in 2005? Did he admit to doctors 15 years ago that he used performance-enhancing drugs?
Starting in the late 1990s, did Armstrong defraud the U.S. Postal Service, a team sponsor, by colluding with teammates to cover up doping? Did he engage in mail fraud and money laundering by trafficking in banned substances?
Armstrong's lawyers complain that their client is the focus of a criminal probe in search of a legal theory.
"Typically, when federal prosecutors initiate investigations they already know the crime that they are investigating - drug dealing, public corruption, organized crime," said former federal prosecutor Michael Pelgro, who has no involvement to the Armstrong probe.
"Here it appears the prosecutors are trying to determine what the credible facts are and then trying to determine whether those facts amount to a federal crime," said Pelgro, now a private attorney in Boston who defends corporations and their executives in criminal investigations.
THE CREDIBILITY OF LANDIS
Landis took a banned performance-enhancing drug to win the Tour de France in 2006. He denied it for five years before changing his story last May at the same time he turned against Armstrong.
In between, Landis raised more than $1 million from now-former friends to fight the drug allegation and publish a book.
The Armstrong camp says Landis's motive is money - that he is seeking to cash in with a False Claims Act lawsuit aimed at potentially recovering millions of dollars from Armstrong for denying his own drug use.
With Landis's credibility at issue, lawyers on all sides agree Landis is unlikely to be called as a prosecution witness if charges were brought against Armstrong.
Landis's switch from denial to admission would be "fair game for cross-examination" by Armstrong's lawyers if prosecutors ever put Landis on the witness stand, said Brian O'Neill, a leading California trial lawyer at Jones Day in Los Angeles.
DRUG TEST DISPUTES
Landis's accusations go beyond Armstrong to implicate the governing bodies of the sport.
For example, Landis said Armstrong and longtime coach Johan Bruyneel paid Hein Verbruggen, former president of the International Cycling Union, to cover up a 2002 test at the Tour de Suisse that purportedly showed Armstrong had taken the blood-booster EPO.
One problem: Armstrong won that Swiss race in 2001 but did not even compete there in 2002.
Verbruggen said there was never any positive test. The president of the International Olympic Committee, Jacques Rogge, said, "To my knowledge it is not possible to hide a positive result." The cycling body issued a statement denying changing or concealing a positive test result. Bruyneel said, "I absolutely deny everything (Landis) said."
Verbruggen said Armstrong made one visit to cycling's headquarters at Aigle, Switzerland, in 2002 after the center's new indoor training track opened. "We had a lot of the pupils and youngsters there," Verbruggen said. "It was a great thing for them to be in the picture with him."
The French sports daily L'Equipe reported in 2005 that Armstrong samples from 1999 showed traces of EPO after being retested in 2004.
Dutch investigator Emile Vrijman, appointed by cycling's governing body to investigate the handling of the urine tests by the French national anti-doping laboratory, said tests on the samples were conducted improperly and fell so short of scientific standards that it was irresponsible to suggest they "constitute evidence of anything."
But that wasn't the last word.
World Anti-Doping Agency chairman Dick Pound countered that the Dutch investigator's report is full of holes. The issue faded, only to be resurrected in the criminal investigation.
The investigation's most recent high-profile event was a trip by U.S. investigators to France in mid-November for two days of talks with police officers and other officials from at least three European countries where Armstrong and some teammates competed and were tested.
THE HUNT FOR EYEWITNESSES
The Holy Grail in the Armstrong investigation would be credible witnesses who say they saw Armstrong take performance-enhancing drugs.
Three lawyers familiar with the probe said they believe prosecutors have heard from witnesses who say they "understood" Armstrong was doping. But investigators are seeking harder and more incriminating testimony than that.
Even if investigators can overcome these obstacles and assemble evidence of a crime, prosecutors would have to enter a courtroom likely full of potential jurors well aware of Armstrong's compelling life story: A cancer survivor and sports hero whose foundation has raised millions to help others.
Lance Armstrong: http://www.lancearmstrong.com/