"It's a 'he said, she said' case. They don't have any DNA. I don't think the woman even had a medical exam." So started a conversation between a real rapist and a helpful patrol officer, who apparently had just contracted a medical disease occasionally found in police work known as the dreaded "cranial-rectal inversion."

For some reason the cop told the crook that the homeless woman he had actually punched into unconsciousness and raped a few days ago had not undergone a sexual assault exam by a forensic nurse. So the bad guy, when he was questioned later by two sex crimes detectives, knew he was in the clear. At that moment in time, he was not just a "suspect," as in, he might have done it, but he was a true sexual predator with previous convictions for violence and prison time.

When those same detectives questioned the rapist later and said they had evidence to nail him on the assault, he looked at them directly and said, "You won't find my DNA, unless tennis shoes leave DNA. All I did was walk up and talk to her."

Puzzled as to how the suspect already knew the victim had not been examined, the detectives met with their patrol pal in blue, only to learn he was the one who had told the suspect all he needed to know.

Prosecutors want to keep their high conviction rates for sexual assault cases. So without sexual assault exams of the victim and the suspect to provide DNA as proof that the act took place, no charges were filed against the man who most likely raped the homeless woman.

You don't want this to happen to you. Here are some reminders of other wrongheaded ideas that could lead you to say or do something you shouldn't and royally muck up a case.

Wrong:

Go ahead and explain to suspects some legal stuff that might have evidentiary value later. Be a good sport and tell the homicide suspect that the guy in the back of the ambulance got shot three times in the back and once in the head with a .45. Help the nice rapist out by telling him that we can't find the victim's bloody clothes or that she is mentally ill, so the district attorney probably won't issue on her case anyway.

Better yet, don't bother to impound anything from inside that filthy duffel bag carried by the suspect or the victim. Who wants to go digging around a place where bloody or semen-covered clothes, knives, money, drugs, or other fruits or instrumentalities of the crime may be hidden?

In a rare case of double cranial-rectal inversion, a patrol officer who had responded to a rape scene was told by his patrol sergeant (a man who had presumably passed a promotional exam and sat through an interview panel), "Don't collect that used condom. Just take a photograph of it." So he took the photo as ordered and left it there, presumably for the victim (or someone) to dispose of that seemingly trivial piece of sexual assault evidence later.

Solution:

When in doubt about evidence, shut up and impound everything. If it looks like evidence, if it's on or carried by the victim or suspect, or if it belongs to someone who may be a victim or a suspect and it's nearby, collect it.

Wrong:

Go ahead and give the suspect some free legal advice: "If I were you pal, I'd get myself a good lawyer; you're gonna need it."

Solution:

Be like Zeus in the field; observe from on high. Once the scene is stable, watch, listen, and wait. Don't make any comments about the situation, to anyone other than other cops, and in low tones at that.

Reading the Miranda warning to an angry, frightened, or vocal suspect right after he is arrested is what TV cops do. Good cops say nothing and let suspects make as many unsolicited statements as they want, in the field, en route to the station, or on the way to jail. Let them hang themselves with their words, which is all the more reason to buy a small tape recorder and leave it running in your patrol car during their monologues.[PAGEBREAK]

Wrong:

Radio silence, police code words, and investigative jargon are for TV cops. Let suspects, victims, and witnesses (who could be interchangeable now or later, depending on the type of case) hear your radio boom across the street, as it blasts out such interesting tidbits as, "Our victim couldn't ID the guy," "the evidence techs say they didn't find the knife at the scene," "the second suspect is not, repeat, not in custody," or "the hospital says she's not gonna make it."

Solution:

Maintain good radio discipline by using an earpiece. Your radio is your officer safety lifeline, your access to information via your dispatcher, and therefore it needs to be protected. Go back to the good old days and start reusing your 10 and 11 codes, and the related police jargon that was designed to keep the bad guys, and their friends and family, in the dark as to what you and your partners are doing or will do.

Wrong:

To make future on- and off-duty officer safety even more challenging, please tell anyone (suspects, witnesses, victims, civilians) where your on-call detectives are coming from. Say, "It may take awhile for her to get here. I think she's driving in from [insert the name of the neighborhood where the detective actually lives]." This is so very helpful for our stalker friends. Knowing where the investigator lives makes it easy for the Internet savvy or just-out-of-jail suspect to go to that community and scout around until he finds the detective eating with her family at a popular restaurant or coaching his kids at the only soccer field in town.

Solution:

If you must explain any delay, say, "He or she is coming from our headquarters." Your best approach is to be intentionally boring, vague, and non-committal. When a gangster asks, "Am I gonna be talking to Det. Smith from the Gang Unit? I hate that guy!" your answer should always be, "That's not something I know or can say right now. We are waiting for an investigator, so just sit tight and you'll know soon enough."

Wrong:

Not only does it not matter what a cop says to suspects or victims, it doesn't matter what victims say. Don't bother to take high-risk victims seriously. This includes prostitutes, mentally ill people, the chronically homeless, informants, and lifelong substance abusers. Whatever crimes they said happened to them probably didn't occur because they're all known liars. Besides, it's their high-risk lifestyles, where and who they hang with, and what they do to survive, that's the real reason they got punched, raped, stabbed, or shot in the first place.

Solution:

Any victim can provide helpful information. For example, prostitutes have survived sexual assaults by men who were later found to be serial sexual murderers. This points to the fact that whether or not you agree with the morality of their lifestyle, they can be invaluable resources. One phone call from a prostitute you know about a customer who asked for a highly unusual sex act could lead you (and a state or federal serial murder task force) right to the guy.

The homeless and other street people have a lot of free time on their hands and they see things you don't see from inside your rolling office. Maybe they want to tell you about someone or something they saw out of civic duty, to get a few bucks or some food from you to help them get by, or because they want a predator to stay away from them. You should take their calls, tips, and comments, no matter how sketchy they sound. One small piece of new data (cars, plates, nicknames, tattoos, etc.), coupled with something other cops or investigators already know, could break a multiple-victim case.

And here's some bonus advice in the same vein. Don't give any case-related information to people who, at the time you encounter them, might seem like witnesses, bystanders, or strangers who have wandered over from somewhere else. These same people could be friends or family members of the suspect and have a strong desire to ask you anything that can help their loved one or beloved friend go free. It's always best to say as little as possible in these situations. Any sensitive information you provide could come back to bite you—and everyone else involved in the case.

Steve Albrecht worked for the San Diego Police Department from 1984 to 1999. His police books include "Streetwork," "Surviving Street Patrol," and his latest, "Tactical Perfection for Street Cops," all available from Paladin Press. He can be reached via editor@policemag.com.