First on CNN: Secret Service concludes cocaine investigation, no suspect identified

The Secret Service has concluded its investigation into the small bag of cocaine found at the White House and has been unable to identify a suspect, according to a statement from the US Secret Service.

Secret Service officials combed through "security systems" and indexed "several hundreds individuals" who entered the West Wing in the days preceding the discovery and were unable to identify a suspect, according to the USSS statement. The Secret Service said FBI lab results from the packaging found "insufficient DNA" and could not retrieve any fingerprints.

"Therefore, the Secret Service is not able to compare evidence against the known pool of individuals," a statement from the USSS said.

Investigators were also unable to identify the particular moment or day when the baggie was left inside the West Wing cubby near the lower level entrance where it was discovered.

"There was no surveillance video footage found that provided investigative leads or any other means for investigators to identify who may have deposited the found substance in this area," the agency's statement said. "Without physical evidence, the investigation will not be able to single out a person of interest from the hundreds of individuals who passed through the vestibule where the cocaine was discovered. At this time, the Secret Service's investigation is closed due to a lack of physical evidence."

A source familiar with the investigation told CNN that the leading theory remains that it was left by one of the hundreds of visitors who entered the West Wing that weekend for tours and were asked to leave their phones inside those cubbies.

The cubbies where the small bag of cocaine was found is a blind spot for surveillance cameras, according to a source familiar with the investigation. While there's surveillance around where the bag was found, cameras are not trained directly on the West Wing cubbies near the lower-level entrance where it was discovered, the source said, making it difficult to identify who left the bag behind.