The burglar, who appears to be female, broke into a business in the town and was filmed on CCTV stealing several items.
She was wearing a large Rudolph mask, which she briefly took off near the end of the footage.
Fort Collins police appealed to residents with information about Santa’s wayward helper to tell them “so we can notify St Nick”.
The burglary was in the early hours of 18 December.
But, along with releasing the CCTV footage, police also tailored the classic Christmas song to back up their appeal.
Rudolph the Red Nosed Burglar
Had a very shady scheme
And if you saw the video
It would want to make you scream.
All of the other burglars
Used to steal without disguise
They weren’t like this Rudolph
She’s different from the other guys.
On one foggy December eve
Rudolph came to steal.
Broke into a Hickory shop,
Never expected to see a cop.
Oh how the camera caught her
As she committed burglary
Rudolph the Red Nosed Criminal
We need your help with her I.D.
After the burglary received some publicity on a US TV station, police said they had received “quite a few requests for a musical rendition”.
Accordingly, “Officer Sarah”, described as someone who “doesn’t appreciate criminals defaming beloved holiday icons”, lent her singing voice to the cause.