Does this happen in real life??

The CSI's don't do the detective work like Mac, DB, and Horatio.

The only thing that does happen that is true is the collection of evidence but the time for processing is different.

Sometimes the little things do make the difference, sometimes its ridiculous. In Indianapolis DNA was found on the cheek of a rape-murder victim. It was traced to a co-worker of the victim. It seems the two shared a bagel and coffee after work, and the guy licked his fingers to wipe bread crumbs from his co-workers cheek. In CSI this would have broken the case.



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I grieved I had no shirt until I met a woman who had no pants.

In the 1980s Atlanta was terrorized by a killer of children, if memory serves 20 children were found dead or went missing over the course of several years. When they finally acquired a suspect Wayne Williams one of the pieces of evidence used to convict him were carpet fibers found on some of the victims that matched the carpet either in Williams' home or car trunk.

If the series were based on reality, it would be incredibly boring. CSIs are all lab rats. They do not sit in on interviews and show the evidence to the criminal. They also don't wear thousand-dollar suits and go around toting guns in the field.
In reality, its the DA who tells the case detective to run DNA if it is needed. DNA profiling is expensive and it takes up to a week for the dye to set. More often than not it is toxicology that is more important than DNA.
In most big-city crime labs, the CSI are not cops. The head of the lab doesn't get to spend any time getting his hands dirty because he is too busy in court or behind a desk doing paperwork.
The majority of cases are settled after weeks or months of assembling evidence, both large and small. Most of the evidence may not even make it to court if you have an unfriendly judge or a plaintiff who has hired a savvy attorney.

I'd enjoy the sandbox if my toys weren't costly & my playmates didn't get a bang outta their fun

These shows are 99% fiction. While there are real life procedures for some of the work they do on these shows, these shows are ridiculously inaccurate in all sorts of ways, not just the CSI work. Pure fantasy.

I worked in the Laboratory Division of the Phila. PD, and, although I enjoy these CSI-type shows, I watch them primarily for the "whodunit" aspect of the plot.

It's already been mentioned here, and rightly so, that these techs (they were known as "evidence technicians" in Philly) are predominantly civilians who collect and process physical evidence.

Although there were a few sworn police officers who were also evidence techs, they did not interview suspects. That's a job for the investigators, who are police officers with the rank of detective.


gravedeparture.com

In real life no police department has the resources that these guys have. I wanna add that Mac and Sheldon have an encyclopedic knowledge of everything -- highly unlikely in real life.