Dateline   |  March 10, 2012

'Internal Affairs', Part 2

For more than 20 years police suspected a robbery involving two men . But a DNA test on the saliva sample from crime scene point to a woman killer. And soon there are five suspects, including a former co-worker and a former girlfriend of Sherri's husband.

Share This:

This content comes from Closed Captioning that was broadcast along with this program.

>>> by 2009 , the sherri rasmussen case was as cold as they come. but then came that monday after the super bowl when detective jim nutall started picking through that old case file and made a remarkable discovery. the dna test that had been conducted on that bite mark back in 2004 .

>> in that lab report , it indicated that the suspect that had bitten sherri rasmussen during the struggle was actually a female.

>> reporter: a woman. not two male burglars as the original detectives had suspected all those years. once they realized that a woman was involved why did it take four years until you finally picked it up? what was the department doing in the interim?

>> from what it appears investigators may have followed the initial theory of this crime, that in fact it was a burglary.

>> reporter: and that there was a woman involved in the burglary?

>> that there was a woman involved in the burglary. looking back in hindsight, it was an opportunity that may have slipped through our hands as an organization.

>> reporter: but now nutall took a look at the crime scene photos and began to develop his own very different theory. remember, sherri rasmussen was shot at point blank range after a violent struggle. and despite the stereo equipment stacked by the front door, very little was actually stolen.

>> the suspect made it appear to look like a burglary. they staged it to mislead the initial investigation in 1986 . she was executed.

>> reporter: in other words, someone had wanted sherri rasmussen dead. so now nutall dug deeper through the file looking for names, female names.

>> we had five women that would have had access to sherri and perhaps at least some of them may have had a motive to harm her. three of them we eliminated almost immediately for insufficient motive.

>> reporter: but there were still two names left. one of them was a co-worker.

>> a woman named debra that worked with sherri rasmussen at glendale hospital. this person of interest was later replaced by sherri rasmussen in an official capacity, and problems followed almost immediately after that.

>> reporter: there was bad blood between them?

>> there was a motive.

>> reporter: debra had moved to northern california . nutall asked local law enforcement there to watch her and secretly try to snag a sample of her dna for comparison testing. in the meantime, nutall learned more about the second woman. he contacted john ruetten, sherri 's former husband, now remarried and living in san diego .

>> john explained that he'd been involved in a dating relationship with stephanie lazarus .

>> reporter: stephanie lazarus , that was the other name still on the short list of suspects. nutall pressed ruetten for more on their relationship, which had started when they were both students at ucla. they dated on and off until john got engaged to sherri . but even then -- you're convinced that the relationship that john had with stephanie lazarus overlapped with the relationship he had with his wife?

>> we know from john that there was at least on one occasion where he was engaged that he was intimate with stephanie lazarus . there was a love triangle . and stephanie lazarus had deep feelings for john ruetten and may have had a motive to harm sherri rasmussen .

>> reporter: was sherri 's kill are a skornd lover? or a jealous co-worker?

>> we had two women on the list who, in our opinion, had a motive to harm her.

>> reporter: debra 's a nurse.

>> correct.

>> reporter: and stephaniey lazarus ?

>> correct.

>> reporter: a few weeks later cops in northern california tracked down debra and secretly scooped up a sample of her trash which contained dna. it was sent to the crime lab in l.a. for analysis and 72 hours later came an answer.

>> she was not the donor of the dna profile from the bite.

>> reporter: that left just one possible suspect, number five on the list, john ruetten's ex-girlfriend, stephanie lazarus . nutall called the rasmussens.

>> we came home and there was a message on our phone from a detective, that they wanted to talk to us. and i thought, oh, yeah, right. i thought it was just another false hope.

>> reporter: this is detective nutall.

>> right.

>> he said that we're opening the investigation.

>> they were upset with me. sort of like detective where have you been for the two decades.

>> reporter: now he explained it all, how he told detectives back in 1986 that someone was stalking his daughter sherri , a woman with crazy eyes , the ex-girlfriend of sherri 's husband. he had never known that the girlfriend's name was stephanie lazarus , but he did know something else about her, something very important. and by this time detective nutall knew it, too.

>> he was very cautious of what he says, but he said that we'd be hearing more from him.

>> reporter: nutall had ample reason to be cautious because he learned that stephanie lazarus wore the same badge he did.

>> we now have a los angeles police officer as a person of interest in a murder case.

>> reporter: and you thought, i've bitten off more than i can chew. chew.

>> toto, we're not in kansas any more. that changed everything. a top secret information as detectives go after one of their own.

>> it was a difficult phase of our careers. she worked our unit. i had worked side by side with the