DENVER (KDVR) — Police in Denver received a tip about the Denver-Lakewood shooter a year before he killed five people and wounded more in an apparent revenge-fueled shooting rampage.

Denver Police Chief Paul Pazen said a day after the Dec. 27 shooting that there were two separate law enforcement investigations into the shooter, Lyndon McLeod, but neither resulted in criminal charges.

On Tuesday, the department released more details on what they described as “the one investigation involving the Denver Police Department,” which happened in January 2021:

In early January of 2021, the Denver Police Department (DPD) received a tip from an individual in Germany citing several concerns involving Lyndon McLeod. One element was possible theft/fraud involving a potential victim outside of Colorado. At the time this tip was received, DPD could not link McLeod to a Denver address provided in the tip and had no reason to believe he was living in Denver. A Denver Police investigator contacted the potential theft/fraud victim out of state and no Denver connection was established to the alleged crime.

DPD is reviewing the investigation, but based on our initial review, there was not sufficient evidence to file criminal charges or a legal basis for monitoring McLeod at the time.

Denver Police Department on Lyndon McLeod

Denver Police did not release further information about that investigation, nor did they release what they know about a second one.

In a prior inquiry, the FBI also would not elaborate on whether they had investigated the gunman in the past, although they did say “the perpetrator had previously come to the attention of law enforcement.”

Gunman’s troubling paper trail

Police have not released much information about what they have learned about the killer, but people who survived his attacks — and even his own self-published writings — offer a glimpse into his motives.

McLeod killed five people and wounded two others, including a Lakewood police officer who ultimately killed him, and he attacked another man who was able to survive while his girlfriend and baby hid nearby.

One of the people killed was a hotel clerk and artist. Another three of the victims worked in or owned tattoo shops, as was the man who survived the gunman’s attacks, Jeremy Costilow.

Costilow told FOX31 that the gunman had threatened him for years, sending him threatening flyers and even writing the threats in a self-published series of books.

In the books, the gunman wrote under a pseudonym, but the main character shared his name and committed 46 murders in a single night against people he felt had wronged him in the past.

He wrote about targeting Costilow’s tattoo shop as well as Alicia Cardenas, a tattoo artist who he ultimately killed. He also described in detail the killing of Michael Swinyard, a man featured in the book as a former business partner.

The book was self-published on Amazon in 2018 but was pulled from the site after the killings.

Police say the investigation into the shooting, which spanned Denver and Lakewood, is ongoing.