The Marilyn Mystery

Eleven years ago, 67-year-old Marilyn Arnopol was killed with a claw hammer. Suburban authorities questioned a Chicago Police officer about the crime.

The murder case up in suburban Northbrook is still open. Police sources say the now-former Chicago cop is still considered the leading suspect, but neither he nor his suspected accomplices have been charged.

There is a new police chief on the scene in Northbrook, with fresh determination to heat up the cold case and arrest those responsible.

December 20th, 1996. Marilyn Arnopol, a widow and mother of five, is found dead at the bottom of her basement stairs, battered with a claw hammer. Northbrook Police find physical evidence at the scene of the crime suggesting at least two people are involved in the murder.

Immediately, detectives focus on Alex Sierra, a Chicago Police officer. At the time, Officer Sierra is living with Marilyn Arnopol's daughter Vera in a Northwest Side apartment, and they have a young child. Also at the time, he owes the victim $8,000.

"He borrowed the money from Marilyn Arnopol, saying he was going to take this money and put it down as a down payment on a repossessed house and he needed the money immediately, the same day," said Steve Jamerson, Arnopol's son-in-law, in 1998.

The Shakespeare District officer tells detectives he had nothing to do with it. Investigators determined Sierra had tried to repay the $8,000 to Arnopol but that his checks bounced. The last check bounced the day before the murder, a day that phone records show Marilyn Arnopol tried numerous times to contact Officer Sierra on his pager.

"We have not gotten answers from him on what has happened to the money or his side of the story," Jamerson said.

Investigators obtained cell tower records showing that Sierra's phone was used near the Arnopol home the day of the murder. And with no sign of forced entry, police concluded that Arnopol knew her killers.

"This incident does not have the markings of a random type of incident. It looked like this one was particularly targeted for this crime," said Sgt. Mike Green, Northbrook Police.

Alex Sierra was thrown off the Chicago Police force before he pleaded guilty to federal conspiracy charges, a case unrelated to the Arnopol murder.

Sierra had held up a grocery store while flashing his police badge and identifying himself as an officer. He now lives in an Oak Park home, having been released from prison a few months ago, after serving most of a 10-year term. He and his wife said told the I-Team that the Arnopol case is in the past and they don't want to talk about it.

Northbrook Police also declined an interview for this story, even though authorities often encourage publicity to rekindle old leads.

Something the victim's son said a decade ago still stands.

"Anybody that does something like this should be prosecuted to the full extent of the law, and we owe it to our mother and to ourselves, you know, to really do what we can to have some sense of closure, at least from that sense," said Michael Arnopol, the victim's son, in 1998.

Some family members currently express concerns about talking publicly because Alex Sierra is out of prison.

Northbrook Police are staying low-key for another reason. They say they don't want to spoil new investigative leads that could help them bring an end to the Marilyn mystery.

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