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Roberts' first job was reporting for a small cable station in Westminster, Maryland then moved on to San Diego, California, where he was a writer and field producer for NBC affiliate KNSD. From there he went on to be a general-assignment reporter with ABC affiliate KLKN-TV in Lincoln, Nebraska.
Then Roberts became a nightly news anchor and investigative reporter for Fox affiliate WFTX-TV in Fort Myers, Florida, and later for WAVY-TV, an NBC affiliate in Norfolk/Portsmouth, Virginia. At WAVY-TV, he co-anchored an afternoon newscast and was also the station's investigative and consumer correspondent.
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Roberts resigned from CNN on May 1, 2007, to settle in the Washington, D.C., area and pursue "new journalistic opportunities".
That opportunity was a co-host and correspondent on the syndicated entertainment programs Entertainment Tonight and The Insider. After co-hosting The Insider, naked pictures of Roberts surfaced that people claimed they've found online at Manhunt.net.
While he was at The Insider, producers would not let him talk about being gay (even though he wanted to) or address the story with the press. Then, that February, Roberts was unexpectedly let go from the program. He went back to traditional news working a correspondent for national CBS News.
He later sat down for an interview with The Advocate about the situation. "I never put inappropriate pictures of myself on a public website. For me it was really hurtful, for [my boyfriend] Patrick and I it was terribly painful, and I'm sure anyone reading this will realize that what happened was something that we needed to deal with on a personal level. And we've dealt with it — we've closed the book on that issue and moved on."
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Roberts has also anchored at the news desk on the weekday and weekend versions of The Today Show for NBC News.
From December 2010 thru February 2011 Roberts anchored the 3 p.m. (Eastern time) hour of MSNBC.
He filled in for Keith Olbermann as the host of MSNBC's Countdown with Keith Olbermann when Olbermann was suspended from MSNBC for making campaign contributions to candidates in the U.S. 2010 elections.
On February 28, 2011 he began anchoring the 11 a.m. (Eastern time) hour of MSNBC.
“Thomas is a very talented anchor who has impressed all of us over the last year,” said Phil Griffin, President of MSNBC. “With his addition, we’re continuing to build a truly outstanding dayside anchor team.”
Roberts received a 2002 Emmy nomination and a Virginia Associated Press award for his work on the documentary, “Parvo Puppies" and an Edward R. Murrow award in 2001 for a documentary that he produced titled, “When Parents Don’t Pay.”
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He discussed his abuse in a special segment on CNN's Anderson Cooper 360 called "Sins of the Father" which aired March 12, 2007.
Roberts publicly acknowledged that he is gay while speaking at the annual convention of the National Lesbian and Gay Journalists Association (NLGJA) in Miami, Florida, in September 2006.
His comments were first made public by journalist Johnny Diaz, a staff reporter on The Boston Globe's living/arts section who attended the conference and wrote about it on his blog, Beantown Cuban. Diaz's report quickly was picked up by major gay media outlets Gay.com and The Advocate online.
Along with Craig Stevens, a co-anchor of Miami's WSVN Channel 7, and other local gay anchors, Roberts was a member of a panel called "Off Camera: The Challenge of LGBT TV Anchors." He told the audience that the conference was the "biggest step" he had taken to really be out in public and that he had slowly been coming out at CNN over the past several years.
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On September 15, 2006, Christie Keith, a reporter with the website AfterElton.com, published an interview with Roberts, who stated that he actually came out to coworkers in 1999, when he was working at WAVY in Virginia. "I was happy, I was in a relationship, and I was very proud. I had the support of family, and of my friends. It was … about not wasting any more time. I'd wasted enough time." He went on to say, "Hopefully, everyone, gay or straight, journalists or doctors or otherwise, can overcome that obstacle, because it stands in the way of you being the best you can be, with your job, with your family, with everything, and not have to be afraid anymore."
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He has been in a relationship with his partner, Patrick D. Abner, since 2000.