Two serial rapists are on the loose in the Boulder area, linked to two different rapes by DNA evidence, Boulder police said Tuesday.

Police said that DNA evidence links an April 26 sexual assault, which occurred on the Boulder Creek Path, to a Feb. 28 rape -- a rape that previously had not been reported by the Denver media, 7NEWS reported.

However, police do not think these two sexual assaults are linked to a rape on the University of Colorado campus on April 20.

The Colorado Bureau of Investigation said that DNA recovered from the scene of the Feb. 28 crime matched DNA recovered from the Miami Dolphins baseball cap that was left at the scene during the April 26 sexual assault.

The DNA profile has been run through the Colorado DNA database but there was no match, investigators said. The DNA profile will be run through the national database next week to see if there are any matches.

In the meantime, Boulder police are asking the public to help identify two men who are pictured in two composite sketches.

The sketches were made with the help of the Feb. 28 rape victim, who was sexually assaulted near 13th Street and Arapahoe.

The 21-year-old woman told officers that she was in the downtown Boulder area when she became separated from her friends at about 3 a.m.. A Hispanic man, between 20 and 24 years old, approached her and offered to help her find her friends but he instead led her to the place where she was eventually sexually assaulted by two men, police said.

The first man (pictured, above left) is described a 5 feet 8 inches, 180 pounds, with dark brown hair and dark eyes. At the time, he had two days of facial hair growth and was described as "scruffy." He was last seen wearing a reddish/orange plaid button up shirt, baggy blue jeans and a dark leather jacket.

The victim said that he spoke broken English and the other man only spoke Spanish.

That man (pictured, above right) was also described as a Hispanic male between 20 and 24 years old. He was taller, 6 feet 2 inches tall, with thinner build and dark hair. He was described as "clean cut" with a "standard" haircut. He was seen wearing a solid dark sweater and blue jeans.

After reporting the assault, the victim was treated and released from a hospital.

A crime scene search of the 1700 block 14th Street yielded possible biological evidence, which was later submitted to CBI for analysis.

The April 26 occurred just before 3 a.m. at the Boulder Creek Path near Boulder High School's soccer field.

The sexual assault was interrupted by two people wandering by, who tried to chase down the two men but were unsuccessful.

The victim sustained minor injuries. She was transported to a hospital, where she was treated and released.

"With the DNA connection between the Feb. 28 and April 26 cases, and the difference in the suspects' descriptions in the Feb. 28 and University of Colorado cases, detectives now do not believe that there is a connection between the University of Colorado and Boulder cases," said Boulder police Detective Sgt. Kerry Yamaguchi.

Detectives from the two agencies will continue to share information and leads as needed.