The other night while flipping through the channels, I came upon the new ABC show, Detroit 1-8-7, and decided to give it a shot. The show is not bad and being a Soprano's fan, I like the cast. One of the things that I always enjoy seeing is the crime scene investigations and forensic techniques shown on TV.
In this episode, the police took a painting made by the suspect and compared the blue paint used to spray-paint the word "fraud" on the murder victim's car. They told the suspect that they had their crime lab analyze the paint and matched the two samples. This was "proof" that the suspect committed the homicide because his paint was found on the car. He quickly confessed.
As a Washington, DC criminal defense lawyer, I thought it might be interesting to talk about how this would happen in real life. First, the sparsely-funded DC Metro Police Department would send the sample to their crime lab, where it could take weeks or even months to get a result. Contrary to what they show on TV, the police do not have gas chromatography mass-spectrometry equipment in every station. They may have it a central crime lab or even contract with a private commercial lab. The analysis that is eventually performed might tell them the brand of paint used, which would narrow it down to the massive quantity of cans sold by Krylon or Rust-Oleum for example. It is not very plausible that they could narrow it down a specific can or even the store the sold it.
What is true about the show is that the police absolutely could tell the suspect that they had done this analysis and use many deceptive techniques to get a murder confession. The police can and often do lie to suspects being interrogated, so don't believe anything they tell you when you're in the box or charged with a crime in Washington, DC.