Lance Armstrong Interview: Former Teammate Tyler Hamilton Said Cyclist Showed 'Genuine Emotion'

Armstrong tells son 'don't defend me anymore.'

Jan. 19, 2013— -- While critics railed against Lance Armstrong for coming off as detached in the two-part interview with Oprah Winfrey that aired Thursday and Friday nights, former teammate and friend, Tyler Hamilton, told "Good Morning America" today that he felt Armstrong was displaying "genuine emotion."

"I've never seen Lance shed a tear until last night. Before I even heard one word from him Thursday night, I could tell he was a broken man," Hamilton said.

Armstrong's contrition turned tearful Friday when he revealed to Oprah Winfrey how difficult it was to betray his family -- particularly his 13 year old son -- who stood up for the fallen cycling star as rumors swirled that he was taking banned drugs.

Armstrong, 41, choked up when he recounted what he told his son, Luke, in the wake of the scandal.

"When this all really started, I saw my son defending me and saying that's not true…" Armstrong told Winfrey, "I told Luke. I said, 'Don't defend me anymore.'"

Armstrong's interview with Winfrey drew millions of viewers.

It was the first time Armstrong admitted using performance-enhancing drugs and oxygen-boosting blood transfusions to help him win the Tour de France.

"I view this situation as one big lie that I repeated a lot of times," Armstrong said. "I know the truth. The truth isn't what was out there. The truth isn't what I said.

"I'm a flawed character, as I well know," Armstrong added. "All the fault and all the blame here falls on me."

However, Hamilton said any hope for Armstrong's redemption would come if he came clean about others who were part of the doping scandal.

"The question now is where he goes from this, his actions moving forward. He needs to name names," Hamilton said.

READ MORE: Armstrong Admits to Doping

Armstrong was stripped of his seven Tour de France titles in October 2012, after a report by the U.S. Anti-Doping Agency found that he and 11 of his teammates orchestrated "the most sophisticated, professionalized and successful doping program that sport has ever seen."

Despite the admissions of his teammates that they had doped with Armstrong and seen him complete blood transfusions for races, Armstrong condemned the report and denied that he had ever cheated.

As sponsors including Nike began to pull support of Armstrong following the report, Armstrong's carefully-built image began to crumble. He stepped down from Livestrong, the charity he started to help cancer patients after he survived testicular cancer.

"It was a mythic perfect story and it wasn't true," Armstrong said of his fairytale story of overcoming testicular cancer to become the most celebrated cyclist in history.

In the interview, Armstrong explained his competition "cocktail" of EPO, blood transfusions and testosterone that he used throughout his career. He also said he had previously used cortisone.

Armstrong refused to give Winfrey the details of when, where and with whom he doped during seven winning Tours de France between 1999 and 2005, which was the last year he said he doped. Armstrong specifically denied using banned substances when he placed third in 2009 and entered the tour again in 2010.

Investigators familiar with Armstrong's case, however, told ABC News that Armstrong did not come completely clean to Winfrey, and say they believe he doped in 2009.

They said that Armstrong's blood values at the 2009 race showed clear blood manipulation consistent with two transfusions. Armstrong's red blood cell count suddenly went up at these points, even though the number of baby red blood cells did not.

WATCH: Armstrong's Many Denials Caught on Tape

Investigators said that was proof that he received a transfusion of mature red blood cells.

If Armstrong lied about the 2009 race, it could be to protect himself criminally, investigators said.

READ MORE: 10 Scandalous Public Confessions

Federal authorities looking to prosecute criminal cases will look back at the "last overt act" in which the crime was committed, they explained. If Armstrong doped in 2005 but not 2009, the statute of limitations may have expired on potential criminal activity.

The sources noted that there is no evidence right now that a criminal investigation will be reopened. Armstrong is facing at least three civil suits.

ABC News' Colleen Curry and Russell Goldman contributed to this report.