LOCKPORT, Ill. (CBS) — Authorities were searching in Lockport Tuesday in the search for Stacy Peterson – the fourth wife of convicted murderer Drew Peterson who has been missing for 14 years – but Peterson’s sister said she was told nothing was found.

The Illinois State Police Division of Criminal Investigation and the FBI were on the scene searching the Sanitary and Ship Canal near 2400 S. Powerhouse Rd. on Tuesday afternoon, but they did not provide further details.

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At the scene, Stacy’s sister, Cassandra Cales, said she found skeletal remains in the canal in Joliet in May using rented sonar that was brought in from Alaska. Cales said she gave information about the discovery to state police and the Will County State’s Attorney’s office.

On Tuesday, five months later, investigators came to the scene – but found nothing, Cales said. She said she was told the area was clear.

“The area is clear to their standards, but I will be back,” Cales said.

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Stacy Peterson disappeared in 2007. Drew Peterson, a former Bolingbrook police sergeant, has not been charged in Stacy’s disappearance. But Illinois State Police have believed for many years that she is dead, and named Drew Peterson a person of interest.

Stacy And Drew Peterson

Stacy and Drew Peterson (Credit: CBS)

Stacy And Drew Peterson

Stacy and Drew Peterson (Credit: CBS)

As authorities were investigating Stacy’s case, they also reopened the investigation into the death of Drew Peterson’s third wife, Kathleen Savio.

Savio’s body was found in a dry bathtub in 2004. Her death was originally ruled an accidental drowning, but was reclassified as a homicide following a new autopsy when Stacy Peterson disappeared three years later.

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In 2013, Peterson was sentenced to 38 years in prison for Savio’s murder. While in prison for that crime, he was convicted of trying to hire a fellow inmate to kill Will County State’s Attorney James Glasgow, and was sentenced to an additional 40 years in prison.

CBS 2 Chicago Staff