I love old detectives. I have worked with two; they had a combined 60 years of homicide experience between them. I loved listening to their stories, but I can tell you right now that some of what they say is BS. When they tell me a guy is innocent because of the way he reacted to a picture of the victim or that a guy shouldn't be considered a suspect because he showed up early for the interview, I laugh. The first thing a good investigator, especially a cold case investigator, needs to know is that you can't base your conclusions on past experiences because those experiences are not foolproof.

The only way to solve a decades-old murder is through hard work, thorough analysis of the evidence, and plain old witness interviews.

The Back of My Hand

When I begin investigating a cold case, I sit down at my desk with a cup of coffee, notepad, and a pen. I read the case file and jot down anything and everything that stands out to me. Anything that just redirects my attention from the "story" I annotate immediately.

Once I am done, which may take a couple of days, I re-read it. This time I become a little more meticulous in my approach. I repeat a sentence a couple of times or I start to write down times, names, stories that may or may not have a rational explanation.

I continue re-reading that case file until I know it like the back of my hand. I want to know that victim. I want to know what that victim would most likely do given a certain circumstance. I also want to fill my brain with every fact about the case so that when I am in a room with a bunch of people talking about the case, I have an answer to every question that is asked of me. If famed pathologist Dr. Cyril Wecht asks me a question the worst answer I can give is, "I don't know." I learned this lesson quickly in the Marine Corps. The correct answer is and always will be, "I don't know right now but I will find out." Yet I have seen detectives who have investigated cases and can't remember the dates of the homicides or the victim's name. Are you kidding me?

After I have read the file numerous times, I then start working the leads that I have jotted down. I start interviewing people.

The Gift of Time

A cold case is unique because it gives the investigator something the original investigator never had…time.

Sure, the original investigator has the best chance of solving the case because he or she has the best chance to interview people when things are fresh in their minds. The original detective also has the benefit of seeing fresh abrasions, bruises, and scratches on people that a cold case investigator doesn't see.

However, there are two major advantages that a cold case investigator has over the original detective. The cold case detective is not buried by case load and cold cases can be worked at a leisurely pace with no interruptions.

Detectives do not have the luxury of only working a homicide case. When a homicide occurs and is assigned to a detective, his other work doesn't stop. The new homicide takes priority, but his case load continues to pile up on his desk. The robberies, the burglaries, the frauds continue to come in. The detective works those homicide leads until she reaches a dead end and her supervisors remind her about the other cases that are piling up. That is how a case becomes cold. It gets pushed to the side after leads dry up.

A cold case detective doesn't have that problem. So in some ways my job is easier.

Another advantage of being a cold case investigator is that over time relationships change. Couples break up and friendships end, which means they may be willing to share information with me that they denied the original investigators. I can go to these people now and re-introduce them to the crime. I can bring all the memories and emotions flooding back when I knock on their doors. I am bringing something to them that most of them have suppressed deep down inside, and they may feel very differently about the events of the past now than they did just after the crime was committed. This is especially true if they feel guilty about something or angry at another party.

Watching the Suspects

Sometimes, it is the prime suspect's door I am knocking on, whether I know it or not. Usually, I treat everyone as a suspect in a cold case because the simple fact is, I don't know who committed the murder.

I don't let the people I'm interviewing know that I consider them suspects. I treat them like they were friends or witnesses, and I tell them I'm just gathering information. But I watch them; I observe them keenly.

I don't make any conclusions from my observations but I do note them. Some people are nervous when cops come knocking on their doors whether they have something to hide or not. Some people will fidget with their hair or tap their foot because it is what they do, not because they are hiding information on a 20-year-old murder. However, it is something I note because it gives me an insight into this person's normal behavior.

Studying human behavior and listening more than talking is the best way to interpret verbal and non-verbal cues from a suspect. I knew a veteran detective who would sit silently with suspects for long periods of time. And in most cases the suspect would begin talking, unprovoked, to break the silence. The detective did this with me and I fell for it. I couldn't take the silence and it made me talk. It is a very, very effective technique, and I incorporate it into my interviews.

Scene of the Crime

Revisit the crime scene, no matter what. One of the most shocking aspects of my foray into cold case investigations came from a revisit. I have learned you can gauge nothing from photographs.

On one case I stared at crime scene photographs, watched video, and drove by the house hundreds of times. But I never went in the house. Big mistake.

During my investigation into another murder, I was constantly bombarded about the next door neighbor being involved. This was because people couldn't understand how she didn't hear any of the victims screaming or struggling for their lives. So, I revisited the scene of this heinous crime 18 years after the fact.

I was surprised at how incredibly small the entire domicile was, especially the bedroom where the bodies were found. I could never get the correct feel for what those victims went through until I was in the very same room where their last breaths were taken. I was floored, shocked, and frightened by the results. They had nowhere to run. They were killed in a room that was basically the size of a large closet. I never got the feeling of the room size from those pictures or videos; I had to go and stand there for myself.

I then stood in the neighbor's bedroom where she stated she was during the time I believed the murders took place. I had another detective stand in the room where the murders took place and where the bodies were recovered. I began to scream and yell and thrash about. After a few minutes the detective in the other room called me and asked if I had started. I told him I had been yelling and screaming for a minute or so. He heard nothing. Myth debunked. The other detective was now a believer as well. Such experiments and explorations have to be conducted in order to confirm or disprove suspicions and find the truth.

One of the things that I do when I work a cold case is keep a journal of everything I have done in the case. The reason I keep this is twofold. It gives me a quick reference to go back to in order to determine if and when I did something regarding the case. And it can be very helpful when preparing to testify if the case goes to trial. Yes, this "journal" is discoverable, but it doesn't matter because I am putting facts into it, not conjecture. The journal also saves me from flipping through hundreds or thousands of police reports to find a date of when I did something.

No Off Switch

As I have discussed, a cold case investigator need to be curious, be a keen observer of human behavior, be willing to test theories, and be meticulous in record keeping. But there's one attribute he or she needs more than any other and that's dedication.

Dedication is something that cannot be learned. It is a trait you either have or don't have.

The best professional compliment I ever received was when I was told by two different, well-respected fellow officers on separate occasions, "If I was ever lying dead somewhere on a street corner, I would want you standing over me investigating my death." As an investigator, I could not ask for a higher, more humbling compliment.

But dedication takes its toll. One of the toughest challenges faced by any homicide investigator, even those of us who specialize in cold cases, is turning off the case. We go to bed at night and continually think of ways to solve the case or who may have done it or what we could be doing better. For me personally, the victims stay with me and the crime stays with me regardless of what I am doing.

The way I look at my job is this. There is good and evil in this world…and most of the time evil will win, especially in a justice system where the prosecution has to prove a case beyond a reasonable doubt. However, eventually, as in all things, good will triumph over evil. So, just because the bad guys have gotten away with it for years and years doesn't mean that evil prevailed. I am here to even the playing field and hold those who are responsible for heinous crimes accountable for their deeds. I have come to do battle against the murderers, rapists, and other horrendous villains of the world. It is good vs. evil in the purest sense. And I believe justice will prevail.

Kenneth L. Mains is a detective for the Lycoming County (Pa.) District Attorney's Office and founder/president of the American Investigative Society of Cold Cases (AISOCC).