CHICAGO (CBS) — As a Blue Island man sits behind bars accused of raping and murdering three women, his mother insists authorities have the wrong man.

As CBS 2’s Susanna Song reports, Sonny Pierce, 27, has been in jail since August of last year on charges of raping a 15-year-old girl.

She survived, but in three other cases, authorities say Pierce not only raped the women, but then strangled them after meeting them on phone chat lines.

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Pierce has been charged with three counts of first degree murder in the deaths of Kiara Windom, 18, of Harvey; Kimika Coleman, 18, of Chicago; and Mariah Edwards, 17, of Blue Island, according to Cook County prosecutors.

“It hurts,” said Pierce’s mother, Esther Pierce-Pearson. “It hurts.”

Pierce-Pearson believes her son is innocent because that is what he told her.

She said she asked her son point-blank, “‘Are you a murderer? Have you ever murdered anybody? You be honest with me,’ and he told me, he said, ‘Mama, I swear to the living God, I never murdered anybody. I never killed nobody.’”

But prosecutors paint a different picture of Pierce, whose victims were murdered between 2009 and 2010. They had all been strangled.

Cook County State’s Attorney Anita Alvarez said authorities suspect there could be more victims.

“There appears to be somewhat of a pattern here,” Alvarez said. “We’re looking to see if there’s anything else out there or anyone else out there that could possibly have been a victim.”

Authorities said Windom and Coleman were both strangled about three weeks apart in August of 2009. Their bodies were discovered dumped in alleys in Blue Island and Chicago.

Investigators found 20 calls between Windom’s cell phone and Pierce the night before her body was found, prosecutors said. He met her on a singles party line in August 2009, they said.

DNA evidence linked Pierce to Windom, and video evidence refuted his alibis for the times of the crime, Orland Park Police Chief and South Suburban Major Crimes Task Force head Tim McCarthy said.

Windom’s mother, Hallena Johnson, had a warning for other parents about whom they might meet in phone chat lines, as Windom met Pierce.

“Chat lines is not a joke. It’s not a game,” she said. “You never know who you’re going to meet. Your child will come up missing like mine.”

Police also discovered a videotape linking Pierce to Edwards’ murder in July 2010.

“In a very disturbing and chilling discovery, police investigating the murder cases recovered a videotape made by Pierce that pictures him engaged in violent sexual relations with Edwards,” Alvarez said. “This 17-year-old girl appears to be lifeless and we believe that she was, in fact, deceased when the video was taken.”

Edwards’ body has not been recovered, but she was reported missing and hasn’t been seen alive since July 2010.

In Edwards’ case, Pierce told police he invited Edwards to his home to rape her in front of other men, then beat her with the men until she was dead, prosecutors said. He has refused to tell police where her remains are, they said.

Pierce has been in jail since August 20 for the rape of a 15-year-old girl. Prosecutors said he lured the girl from her home into his car, drove her to his home, then dragged her into his home, where he choked her until she passed out, then raped her.

Pierce’s mother said while she will stick by her son, she grieves over what happened to the three teenage girls.

“I feel for those that lost their loved ones, because I’m a mother,” Pierce-Pearson said. “I have nine children; six daughters.”

Pierce was ordered held without bond at the Markham Courthouse Wednesday.

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