Holmes was accused of sexually assaulting a former Dolton employee during a village-funded trip to Las Vegas last year.
Along with his work as a trustee, Holmes is also a well-known gun violence victims' advocate.
The woman publicly made her accusations in a video and appeared at a Dolton village meeting earlier this year.
READ MORE | Former Dolton employee speaks about sexual assault she says she endured from Trustee Andrew Holmes
She is currently suing the village and Holmes, saying she was fired after taking her sexual assault allegations to embattled Dolton Mayor Tiffany Henyard.
ABC7 has reached out to Holmes for reaction to the decision by Las Vegas police to close the case.
SEE ALSO | Activist confronts Dolton Trustee Andrew Holmes over sex assault allegations, taken away by police
READ MORE | Crisis responder Andrew Holmes fired by Chicago Survivors after alleged sexual assault