Law enforcement officials have indicated they are getting closer to discovering the identity of the individual who killed UnitedHealthcare CEO Brian Thompson outside a Manhattan hotel, though experts warn that the path to identifying and apprehending the gunman remains complicated.

Investigators are meticulously combing through evidence, including DNA, fingerprints, surveillance footage, and other leads.

While NYPD investigators appear to be making progress, there are obstacles when it comes to analyzing some of the evidence the killer left behind, according to CNN. “A fingerprint previously obtained by police was unusable for an identification,” the report noted.

NYPD Chief of Detectives James Kenny told reporters during a Friday press briefing that the fingerprint “could be enhanced later in the investigation.” He also noted that investigators were having trouble using facial recognition due to limitations in the technology and the quality of the images picked up by surveillance footage.

Nevertheless, the police have put together a comprehensive timeline of the suspect’s 10-day stay in New York City, tracing his movements to ascertain his possible identity and location. “They will create a movie of his every move,” said CNN Chief Law Enforcement Analyst John Miller.

Miller went on to highlight the importance of preserving evidence such as the backpack that was found in Central Park, which is believed to belong to the suspect. “Their instructions were, ‘If you find it, freeze the location, do not touch it. Wait for the detectives, wait for the crime scene unit and let them package this up,” he said during an interview with anchor Anderson Cooper. This is so that when the case goes to trial, law enforcement can confidently state that they went through the proper procedures.

It is also believed that the shooter could have used a “veterinary gun,” a tool typically used by farmers to euthanize their animals quietly. Miller described the weapon as “practically silent” and “meant for close-up killing.”

New York City Police Commissioner Jessica Tisch expressed confidence that the abundance of evidence will eventually lead to an arrest. "We already have lots of forensic evidence, fingerprints, DNA evidence, [and] a massive camera canvass of the suspected shooter’s movements," she said.

However, finding and arresting the killer might still prove tricky, according to law enforcement experts. Despite New York City’s extensive surveillance network, identifying the killer has been a challenge. “He knows he’s on camera – it’s New York,” Miller said.

Even with the DNA evidence investigators may have found, the authorities could still have trouble identifying him. “Callahan Walsh of “America’s Most Wanted,” told CNN that “If they’re able to pull DNA…but there’s no match to those DNA (samples), it’s going to be very difficult.”

Facial recognition technology can be helpful, but it is not foolproof. Donnie Scott, CEO of IDEMIA Group, noted, “Face is not a fingerprint. It’s not DNA. It’s not used for (an) affirmative match.”

Still, law enforcement remains optimistic about making an arrest. If they are correct, then it will only be a matter of time before they have the individual in handcuffs.