Delving deeper into the personal life of the UnitedHealthcare CEO will play a key role in the investigation: a retired NYPD officer.

Investigators in the shooting death of UnitedHealthcare CEO Brian Thompson are “deeply involved” in his life, including family and friends, a retired NYPD officer told Fox News Digital on Friday.

“In this case, I think the police are really looking, what the investigators are really looking at is the victim because most murders are committed by someone who knows the victim,” Ralph Cilento, a retired detective commander. the NYPD and a professor of police science at the John Jay College of Criminal Justice, explains.

“It’s a very high percentage, as close to 90%, I think. So, apart from analyzing the crime scene, what’s going on legally, what’s recovered the shells and live rounds and the like. [there are] in all murders – not only in this one – there is a deep sinking of the victim.”

He said that even if the deceased did not know the suspect, it is possible that they knew each other “by proxy if someone sent an attacker to kill someone.”

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“So, generally, the way you investigate a murder, among other methods, you start with the victim and then you make specific circles, and usually the perpetrator is there somewhere. Not always, but usually,” he explained.

Cilento also noted that the shooting happened the morning of the Rockefeller Center Christmas tree lighting.

Thompson was killed early Wednesday in front of the Hilton in Midtown Manhattan.

“Now, it’s before the tree lighting, but the way the NYPD works is any information on size starts the day before,” he said. “So, it’s a very bad move, when we can think that there are more policemen on the street.

“So, we don’t know if this guy got past the police with body cameras. So, all these pictures have to be made. It’s a big, hard and boring job. It’s a big responsibility to put everyone together that video.”

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A separate photo of United Healthcare’s corporate headquarters and CEO Brian Thompson, who was killed Wednesday. (Getty I AP Photos)

Cilento also noted that there is a team of investigators at Thompson’s home near Minneapolis.

“Remember that in order to find a clue about the murder, you must investigate the deceased,” he said. “And you go out and around in circles from there – his emails, communication with his wife, and his family members, communication with current and former employees. Was he threatened in any way? Did he just deny the customer that the health care company’s coverage for something? All of these methods require to be observed.

He added that although he was not surprised that the suspect was able to escape “in a short time, his days are numbered.”

He said investigators are putting “a lot of resources” into the investigation so he won’t be caught soon. And it is impossible not to leave an electronic footprint despite the suspect’s attempts to enter his Manhattan hostel before being shot with a fake ID and pay in cash.

A screenshot from surveillance footage released by the NYPD shows the suspect in the shooting of UnitedHealthcare CEO Brian Thompson. (NYPD Crime Stoppers)

Cilento called the suspect using a fake ID and paying in cash just a “bump” in the investigation.

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“They’re running all over the place,” Cilento said. “So, there’s a team in Minneapolis, there’s a team dedicated to video recovery, which in itself is a tedious and difficult task. And it’s not just video recovery.

“Thousands, cumulatively, must go through thousands of hours of video. And there are detectives somewhere going through the video to identify this guy. There are other detectives going through NYPD body cameras on the off chance that he was caught and passed by an officer. The body camera was activated. And the only way to do that is to do it.” and that is tedious and granular work that needs to be seen and I can assure you that it is seen.”