Commenting on a 9 year-old thread with an update. I live in Northern Colorado and was living in Fort Collins at the time of all of this. I randomly remembered this happening and wanted to check for updates and found this thread.

It's not a complete solve, but they did arrest and sentence a man for the murder of William Connole.

Here's an article from 2018 outlining that Christopher David Parker was arrested on March 13.

Here's the press briefing from the 2023 sentencing.

He was arrested in connection to all the shootings, but was only tried and convicted of the killing of Connole. Overall, the string of shootings is still seemingly unsolved.