Prosecutors called Gayle to testify about his relationship with Marni Yang, 43, the real estate agent on trial for killing Rhoni Reuter outside of her north suburban condo in 2007.
The former Bears player arrived at the Lake County Courthouse at approximately 9 a.m. Gayle did not speak to the news media on his way in to testify.
The prosecution alleges Yang was obsessed with Gayle and that she shot and killed Reuter out of jealousy.
In court Tuesday, prosecutors were armed with boxes of evidence. First, they questioned an officer on the stand about a list of women's names found in Reuter's purse. They suggested Yang might have sent the list with a note saying Gayle was seeing all of the listed women.
Gayle says he was not exclusive with anyone at the time.
While on the stand, Gayle said he met Yang at a Bears convention at a downtown Chicago hotel in 2005 when she was a security guard at the convention. She also worked as a realtor. He testified that the relationship started out as business, but he admitted the two did have sex several times.
"It started as meeting and talking about real estate deals...from time to time, it would change into a personal relationship," said Gayle.
The night before the murder Gayle testified that Yang came to his home.
Prosecutor Ari Fisz asked, "Did the two of you have sex?" Gayle replied, "Yes, that happened."
On the morning of the murder, Gayle got a couple of calls and was trying to reach Reuter. He called her cell phone first, and later: "I called her on her home phone. I started to panic with the information I got," he said.
Gayle testified he was questioned for 10 hours by Deerfield detectives. When asked who would have killed Reuter, he gave them the name of a woman with whom he had broken up. Gayle said that the woman was harassing him and other women in his life. He had a restraining order against her.
Also Tuesday, Yang's daughter was subpoenaed by the state to testify against her mother. Emily Yang testified that her mother had accessed Gayle's email.
"She didn't use the word accessing but she had gotten into Shaun Gayle's email account," she said.
Later, the 20-year-old testified that her mother told her she "sent a letter out to all the women so they could find out about each other."
Several witnesses have also testified about a letter that was sent to 17 or 18 women in Gayle's life informing them about the women Gayle was seeing. Yang's daughter testified that her mom told her she sent the letters. A copy of the letter was found in Rhoni Reuter's bag.
A former co-worker testified about Yang's access to Gayle's account. "I knew she was in his personal email because she would say, 'look at this, look at all of the girls he has emailing him.' She was very upset," said Maggie Zimmer. A former friend of Yang's testified that Yang studied emails of one of Gayle's ex-girlfriends. "She sent an email posing as this girl making threats saying she was involved with Shaun Gayle," said Julie Ann Fields.
Monday was the first full day of testimony in the trial, and investigators talked about what they had found in the case and some of the evidence that was discovered.
Investigators testified that Yang prepared for the murder. Officers said they found bank statements and receipts in Yang's trash that showed Yang purchased equipment to build a silencer for a 9mm pistol and books on how to make a silencer.
Prosecutors say Yang was wearing a disguise when she fired several shots at Reuter, who was more than six months pregnant. Some of the shots were aimed at Reuter's womb.
Yang's attorneys contend that prosecutors have unfairly targeted Yang and did not look at any other suspects in the investigation. They also said Yang did not want to have a more personal relationship with Gayle.
The trial is expected to take two weeks. If convicted, Yang faces life in prison.