Investigator Trevor Materasso would not say if investigators believe the same person was involved in both attacks.

"We're limited beyond that to talk in detail or give specifics on how those two connections are made," Investigator Trevor Materasso told 9NEWS.

Over the Memorial Day weekend police say a jogger was attacked from behind at Ketner Lake by a man who used a chemical-soaked rag to try and subdue her. The woman fought off her would-be abductor.

For days, police spoke of a possible connection between the Ketner Lake incident and the Jessica Ridgeway kidnapping but it wasn't until Monday that they officially linked the two cases.

Monday evening, police also told 9NEWS that they have ruled out other evidence that has been recovered as they investigate the Ridgeway case.

Most notably, police say some grocery receipts for garbage bags that were discovered after Ridgeway's body was found are not related to the case.

Meanwhile, investigators are still testing potential evidence that was found by a woman at Pattridge Park on Sunday.

The woman reported to police that she found a "clump of hair" while walking in a field.

Police collected that item and say they are not certain it is hair and are waiting for further testing to determine if it's relevant to the Ridgeway investigation.

Thousands of tips have been received in the Ridgeway case and police are still asking for the public's help.

The FBI and the Behavioral Analysis Unit are asking the public to contact authorities if anyone around them changed their behavior, acted unusual, failed to show up for a family activity or other change that was unusual on Oct. 5 and days after Jessica's disappearance and the Memorial Day weekend.

You can contact the Westminster Police Department on their tipline: 303-658-4336.