When I first started out as a young police detective, I would spend hundreds of hours, often times for naught, trying to solve a heinous or complex crime. After a while, I discovered that if I spent about fifteen minutes with the right person, in the right place, and maybe throw in a cigarette and a candy bar, I could often crack the case. In investigating terms, the right person was an informant. This goes for both police detectives and private investigators. Often times there is someone out there who has knowledge of the case, but you have to use the right approach and do it in the right location, in order to get the right results.
Try not to let police movies or TV cloud your vision of how to work an informant. You don’t approach someone on the street and expect them to talk to you. By doing this, it also shows your lack of knowledge of the street and you won’t be trusted. For police detectives, an individual can be interviewed back at the police station or in the lock up.
I used to scan the daily arrest logs to see if anyone got arrested near one of the crimes I was investigating, or if any of my informants had managed to get themselves locked up. I’d talk to the detective that was handling the individual’s current arrest to clear it with him, and then I’d go and talk to him. It’s amazing how many arrestees, knowing that their looking at going back to prison, will talk to you if you have the right approach. You have to be able to convince them that you will protect them and not reveal their identity. Start small, and once they give something up that appears to be good, that’s when they get rewarded with the coffee or soda. The more they give up, and the bigger the case, is when the candy bars and cigarettes come out. Remember, they get the goodies after they cooperate, not before.
The same holds for private investigators. You can meet with a possible cooperative informant off-site from his workplace or home. Whether you’re a cop or a PI, you always pick the time and location. You want to make sure you’re not being setup.
Different motivations motivate different people to give up information. It can be fear, revenge, retaliation, power, honesty etc. You need to find which one is the one that turns your informant. Find the right one, and your case can be solved.