Updated 03/08/11 - 5:15 p.m.
WAUKEGAN, Ill. (CBS) -- For the first time on Tuesday, former Chicago Bear Shaun Gayle publicly admitted having a sexual relationship with Marni Yang, the woman charged with killing his pregnant girlfriend in 2007.
Yang is on trial for the 2007 shooting death of Rhoni Reuter and her unborn child.
Gayle took the stand in Waukegan on Tuesday. He revealed that he had over a dozen sexual partners, but was also buying baby name books and looking forward to the birth of his child with Reuter, his longtime girlfriend.
Gayle testified he met Yang, a real estate agent at a Bears convention in 2005 at the Chicago Hilton and that their relationship started as a business relationship at first.
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But he admitted the relationship later became a sexual one and he admitted that he had sex with Yang on the night before Reuter was shot and killed in her condo.
Publically, defense attorneys have claimed Gayle was stoic when learning of Reuter's murder, insisting a barber finish cutting his hair.
Gayle's testimony suggested otherwise, saying that while he was at the barber shop, his cell began ringing as a TV producer and then former Bears teammates Emery Moorehead and Tom Thayer told him there had been a shooting in Deerfield and his name was implicated.
"I started to panic with the information I got," Gayle said, adding that he tried to reach Reuter on her cell and home phones. He eventually called Deeerfield police, who instructed him to drive to their offices.
Defense attorney William Hedrick questioned Gayle about his relationship with another woman who began harassing Gayle after they stopped dating in November 2006.
On the day of Reuter's murder, Gayle signed a complaint against that woman seeking criminal contempt of court charges for violating an order of protection he had taken out against her.
Prosecutors have suggested Yang was obsessed with Gayle, hacked into his computer, located the names and emails of 17 girlfriends, and wrote them on an anonymous note to Reuter saying "I think you would like to know what your boyfriend Shaun is doing with a lot of other women."
Witnesses from Yang's son's football practice testified she would brag about writing the letter, composing it in broken English to suggest one of Gayle's foreign girlfriends was responsible.
Yang came to focus her jealousy on Reuter upon finding out Reuter was pregnant, prosecutors have said.
Prosecutors also have said Yang used an elaborate scheme to cover her tracks during and after the murder, including wearing a disguise, building a home-made silencer and using a throw-away cell phone while planning and carrying out the crime.
Yang's 20-year-old daughter Emily also was called to the stand on Tuesday. In whispering tones, she testified that her mother accessed Gayle's email accounts and complained of the many women Gayle dated.
CBS 2's Vince Gerasole, WBBM Newsradio 780's Bob Roberts and the Sun-Times Media Wire contributed to this report.
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