ELGIN, Ill. (CBS) — A former Elgin police officer has been sentenced to 30 days in jail for planting evidence at a crime scene.

As WBBM Newsradio’s Terry Keshner reports, Michael Sullivan, 54, admits to placing a cell phone that was believed to belong to a robbery victim in a case he was investigating on April 27, 2011. He placed it at the scene of the robbery.

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Sullivan admitted to his superiors what he had done and resigned from the department soon afterward. He has since cooperated with police and Elgin prosecutors, according to the Kane County State’s Attorney’s office.

But charges ended up being dropped for the suspect who was arrested in the robbery, according to the State’s Attorney’s office.

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Sullivan, of Sycamore, pleaded guilty to one count of obstruction of justice, and was sentenced by Kane County Judge Allen M. Anderson to two years’ probation, 30 days in jail, and 200 hours’ community service.

He is eligible for a day-for-day credit in jail, which means he could be out in just 15 days.

Sullivan will also have to pay $1,000 back to the Elgin Police Department for the money it spent while investigating him, prosecutors said.

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LISTEN: WBBM Newsradio’s Terry Keshner reports