Information is the currency that criminal investigators deal in. Information is needed to solve crimes and lock up criminals.

The best information comes from honest citizens providing the truth to the police to make their community a safer place. This information comes from victims of crimes and alert witnesses of crimes or suspicious behavior.

Informants are another source of information. Informants can make an investigator look like a hero when they provide good information — but they're typically rather needy and difficult to handle.

Informants come from all walks of life. In evaluating an informant, the wise investigator must first try to understand what is motivating a person to become an informant. The best and most altruistic informants are trying to clean up their neighborhood or workplace or just want a bad person off the street.

Other informants use the police to exact revenge against someone who angered them. This sort of informant knows something about another person and is going to teach that person a lesson. Sometimes, drug dealers will even give information against rival drug dealers in an effort to get police to eliminate the competition.

Mercenary informants will wait until there is a large reward to come forward with information. In my experience, there is a danger of diminishing returns when the reward money used to solve crimes become more than several thousand dollars. The problem with huge rewards is that many mercenary informants will try to play what I call “tip lotto.” In this little “game” the informant just thinks of someone shifty in the area and gives the police that name. The strategy here is the mercenary may get lucky, and the person named might actually have done the crime.

If they gave the right name to the police, they can then claim the reward when the crook is arrested. The mercenary tipster figures the odds are way better than the real lottery. The problem for investigators is it causes a lot of bogus tips that have to be checked out. Bad tips waste an investigator’s most precious commodity — time.

Police informants don't usually receive much compensation for their information.

The vast majority of police informants get paid little or nothing. Only the larger departments have informant funds. I am a firm believer in paying informants for information if they give it on a regular basis. The $20 to $100 given to an informant who solves a major crime can save many hours of investigation, and thereby thousands of dollars of personnel costs.

Some informants are “drafted” into service by the police. These informants find themselves in trouble and offer up information about more serious crimes and criminals in return for leniency in the case against them.

Criminals in police security interview rooms will give up all kinds of information for their immediate freedom. These criminal informants seldom fulfill their grandiose promises of catching the biggest criminal or solving the most difficult crime, so they're charged with everything they were originally arrested for.

Informants are difficult and needy because most are close to crimes and criminals to get information. Many informants therefore get into trouble with the law themselves at some point. When they do, the first thing out of their mouths is the name of their “control” officer and a request to use a phone.

This causes the detective handling the informant to climb out of bed — informants never seem to get in trouble during business hours — and talk to the arresting officers and supervisors to see what can be done for the informant. If nothing can be done that evening, maybe a letter to the court at sentencing can help the valuable informant. Criminal informants take a lot of time, energy and patience to cultivate — but can provide amazing information on occasion.

The last group of informants are those who just like to be around the police and feel like secret agents. These informants are pretty harmless and just like to feel important. They like to give winks and nods to their friends and name drop police officers’ names. They tell their friends, “Yeah I’ve done some work with the cops…you know stuff I really can’t talk about (insert wink and nod here for desired effect).”

A member of this last group came in and gave me information mined from a local saloon. The informant, after many weeks in the bar, had uncovered information that a motorcycle gang was in cahoots with space aliens and assisting a known terrorist organization.

Obviously, information of this magnitude was far beyond the scope and jurisdiction of the Ann Arbor Police Department, so I suggested the informant go speak to the FBI. That’s when the informant told me the FBI had referred her to me. It must have been a payback for the woman with the 18-pound narcotic-sniffing cat I sent them.

Lock it up, don’t leave it unattended, be aware and watch out for your neighbors.

Rich Kinsey is a retired Ann Arbor police detective sergeant who now blogs about crime and safety for AnnArbor.com.