Israel Keyes studied those who were similar to himself. For example, he described Ted Bundy as his "hero," and he relished in the murders of other serial killers. He was also very intrigued by the people who hunt serial killers, especially Roy Hazelwood and John E. Douglas. Both were FBI agents in the Behavioral Analysis Unit. Israel used this info to avoid getting caught. He used the info about how police forces solved the crimes to learn how to avoid leaving traceable evidence. He wanted to succeed at his horrible acts so that he could continue his hobby unperturbed.
His library of books and DVDs about dastardly acts was extensive... and the cops read and watched every single one of these helpful pieces of evidence. Keyes was smart enough to leave a bunch of false clues. One step he took to make identifying bodies difficult was dismembering them. He also triple-bagged the body parts in plastic in order to contain the blood and avoid leaking DNA. Keyes constructed and buried "kill kits" in the areas where he planned to act.
Israel Keyes grew up in an off-the-grid cabin in the state of Washington. He had nine siblings, and he lived in poverty. His parents were Mormons at first, then they joined a white-supremacist church. The boy did not have many friends as a child, and when he found some, a pair of brothers, they also became killers as adults. Keyes enjoyed sojourns into the woods to shoot animals, one of whom was his sister's cat. He developed some awareness of his differentness due to the horror of other kids at his violent tendencies.
Keyes liked taking things from other people, whether it was money, their autonomy and/or their lives. he enjoyed robbing banks in small towns because it was easier to succeed. He enjoyed kidnapping people and then demanding ransom. He raped, tortured, and killed people of all genders and ages. His only preference was "lightweight." He tracked the progress of law enforcement on his crimes.
Israel Keyes was not a person that you wanted to meet alone in a dark alley. You probably did not want him to work on your house either. Some customers of his company, Keyes construction in Anchorage, Alaska, were a bit weirded out by him.
American Predator: the Hunt For the Most Meticulous Serial Killer of the 21st Century by Maureen Callahan, 2019
This was an intriguing read; I first saw mention of this case on the 48 Hours TV show.