This 1950s clip - the 3rd of 4 - follows the police investigation into a man’s death, initially deemed a suicide.  

Begins with a lab technician testing whether the deceased individual had been drinking at the time of death. The technician wears a white lab coat. Vials, test tubes, and pipes are on the counter before the technician. He blows air into or sucks air out of a long glass-like tube, perhaps to mix a substance that’s in the test tube that he’s holding. 

The technician used a standard distillation process to separate the alcohol from the blood - a process taking about 45 minutes. Potassium dichromate and sulphuric acid were added to the distillate and allowed to sit and mix. Then a portion of the solution was put into an electrophotometer. Alcohol in a solution produces various shades of color, which the electrophotometer can read and translate to percentages of alcohol. After getting the results from the intoxication test, it was determined that the deceased individual had not been drinking. 

The lab technician and investigator have a brief conversation. The investigator says that his team still doesn't have a motive for the killing - a reason why the man may have shot himself. When he was alive, the man didn't seem to have any money troubles and appeared to be in good health. But one sticking point was that the man’s wife had asked him for a divorce just prior to his death. 

Samples of the dead man’s liver and stomach from the autopsy are then analyzed at the crime lab for poisons; this is a routine check for deceased individuals if the cause of death has not yet been determined. The lab technician puts a portion of an organ into a meat grinder and turns the grinder’s hand crank. The lab is specifically searching for volatile, metallic, and alkaloidal poisons for each organ; the search is a long and involved process often taking days to complete. The technician pours a hot alcohol solution into a white bowl, mixing the solution with the ground organs. The technician then pours the mixture through a purifying process, which removes substances that might interfere with the test. The technician finally removes any alkaloidal substances from the mixture in case any were present. The resulting mixture is a clear liquid, which is then placed into a spectrophotometer, a large, box-like machine with assorted dials. The spectrophotometer transmits various wavelengths through a sample, and the amount of light absorbed by the sample is then measured and graphed, allowing technicians to determine what substances exactly are in the mixture. In this case, measuring 255 millimicrons, it is determined that the dead man had strychnine in his system. Strychnine is a highly toxic alkaloid. The man had enough of this poisonous substance in his body to kill him. 

As a result of the toxicology test, the narrator says that investigators then tried to determine how the strychnine was administered. So they tested a coffee cup that was found at the crime scene. And indeed, strychnine was also found in the coffee cup - specifically, in scrapings from the coffee cup. 

A lab technician asks the investigator with the wide-brimmed hat whether the dead man was murdered. The investigator says that the man wasn’t necessarily murdered since the man could have taken the poison himself. The technician then wonders why a man would drink poison and shoot himself. The investigator says that’s a good question; he points out that he ordered a man from his team to look at all nearby drugstores to see if they could provide any further answers, or leads, about the strychnine. 

The investigator says that another clue in the case was that the dead man could not type, and yet the dead man’s suicide note had been typed. So the investigator went back to the suicide note and the paper attached to it, a will. A man is seen with a long glass-like device, pumping some kind of substance onto the death message, the supposed suicide note, to make visible the fingerprints that were on it. There’s a close-up of the death message and a reddish fingerprint above the opening paragraph. A black box is then placed over the fingerprint that was made visible on the death message; this seems to be a camera of sorts that’s capable of taking photos of details like fingerprints. 

The voiceover tells us that the fingerprint on the death note was compared with the fingerprint on the coffee cup; both were different, so it was concluded that someone other than the deceased man had typed the death note. It was further concluded that the will could potentially tell an important story. The investigator is seen walking through a door, leading into a dark room. The room is labelled “DOCUMENTS.” 

A man is seated at a desk, looking at both the death note and the will using a magnifying glass. The voiceover says that, after a period of analysis, a big revelation was found about both documents: They had typewriter flaws, leading investigators to conclude that both documents were created using the same typewriter.