Sister of missing mom Stacy Peterson says she found body using sonar, cops searched but found nothing

It's been more than a decade since Bolingbrook mom Stacy Peterson disappeared, but on Tuesday, crews were back out searching again – after Peterson's sister told police she had found a skeleton using advanced sonar.

Stacy's sister Cassandra Cales told FOX 32 Chicago that in May, she used the world's most advanced remote sonar to search the Des Plaines River near the Lockport Powerhouse, which is a power station north of Joliet.

Cales said that she has been searching for years, using more and more advanced sonar equipment, and that in May, she found a skeleton.

"Twenty-two days after my sister went missing, I had live sonar – full flesh female figure –  my sister in the water," Cales said. "The currents, the wakes, the buoyancy – all the stuff I studied. I figured it out with my better equipment and education where she washed up. And I'm not going to stop. If you want it done right, you have to do it yourself."

But on Tuesday, police crews left the river empty handed.

The Illinois State Police said in a statement: "The Illinois State Police with the assistance of the Federal Bureau of Investigation searched an area of the I&M canal near Lockport. This area has been searched before in recent months with unsuccessful results. The search today was also unsuccessful. No further information is available at this time."

"I am beyond frustrated," Cales said. "It's definitely somebody. I can't say it's my sister. But why take so long to go and retrieve something?"

The case of the missing mom drew national attention as her husband, Drew Peterson, hogged the media spotlight. He has long been a suspect in her October 28, 2007 disappearance but has never been charged. He claims she ran off with another man and left her children behind.

However, he is doing time for killing his third wife, Kathleen Savio. She was killed in 2004, her death in a bathtub staged to look like an accident. Peterson was charged and in 2012 convicted of Savio's murder. He is serving a 38-year prison term for Savio's murder, but maintains his innocence. His murder conviction was upheld by the Illinois Supreme Court in 2017.

Drew Peterson will follow that 40 more years after he was convicted of plotting to kill the prosecutor who put him behind bars.

Stacy Peterson was Drew Peterson's fourth wife. When they married, she was 19 and he was 49.