The Jaryd Atadero case is featured in the Missing 411 books and has also been discussed numerous times by David Paulides in various interviews. On his website and in the interviews, Mr. Paulides has cast doubt on the hypothesis that Jaryd was killed by a mountain lion. Here are some statements from his website on that issue [emphasis added]:

“If something dragged him 500+ feet up a rocky, steep incline, his shoes would be banging or dragging on the ground and would undoubtedly fall off, yet they were found near the clothes. When I examined the shoes, there were no scuff marks or significant scratches near the toes or the back of the shoes, which I believe there would’ve been there if he had been dragged up the mountain… Allyn contacted a group of mountain lion experts… The consensus opinion was that a mountain lion had not killed Jaryd. This was based on a lack of serious damage to the sweater near the stomach and neck.”

To my knowledge, none of the experts have been named and no documentation from such experts has been posted online. As a result, the claim persists that Jaryd’s death was, unfortunately, caused by a mountain lion attack.

Here is what I’ve been able to dig up online regarding this claim [emphases added]:

Background Information

A link to a description of the search and rescue conducted for Jaryd:

Click to access news072003.pdf

In Support of the Mountain Lion Attack Claim:

Robert’s Amazon.com comment to the Missing 411 books, posted on Apr 18, 2014 4:28:22 PM PDT, cites two experts who say it was a mountain lion attack and also explains why Mr. Paulides’s assumption about dragging may be incorrect:

“Robert says:.. It was determined in 2003 that he was a victim of a cougar attack. Numerous articles were published to that effect. Evidence was uncovered in June 2003 that positively indicates that 3-year-old Jaryd John Atadero was killed and carried away by a mountain lion. From the initial 1999 investigations, officials had theorized that Jaryd may have been attacked and dragged off by a mountain lion. That horrific possibility emerged four days after his disappearance with news that a dog team and trackers had discovered a small footprint and other subtle signs of Jaryd Atadero that suddenly vanished about 175 yards from where mountain lion tracks were found. Major Bill Nelson of the Larimer County Sheriff’s Office and search commander for the first four days after the boy disappeared stated that as the 1999 search progressed, there were multiple reports of cougar signs and sightings in the area. At that time, the Larimer County Sheriff’s Sergeant Justin Smith said, “It’s certainly consistent with why there have been no solid signs of Jaryd.” … It was the day before Fathers’ Day, June 14, 2003, and the remains were found just about 10 minutes after his father, Allyn Atadero, arrived at the search scene. Allyn was allowed to cradle his son’s tooth next to his heart before it was taken into evidence. Osborne and Watts, respected outdoorsmen and businessmen from Fort Collins, both are positive a mountain lion killed Jaryd.“In my mind I have no doubt at all that he was killed by a mountain lion,” said Rob Osborne. “As soon as we looked at the fleece jacket and looked at the other clothing, “we could see puncture holes from teeth”.It looked to me like he was carried, not dragged, up the slope.” Duggins Wroe, a wildlife biologist from Wyoming, has examined Jaryd’s clothing found at the scene and concluded that damage to the shoulders and upper arms of the pullover are consistent with that caused by a mountain lion grabbing its prey. Sources: Denver Post; 10/05/1999, A1; 10/06/1999, B6; 10/08/1999, B1; 10/10/1999, B5 Colorado Springs Gazette – Telegraph; Colorado searchers fear the lost child may have fallen prey to mountain lion; by Bill McKeown; 10/07/99 The Coloradoan; Punctures in toddler’s clothing convince hikers: ‘In my mind, I have no doubt at all that he was killed by a mountain lion.’ by Miles Blumhardt, Matthew Benson, and Sarah Langbein; 06/12/2003 The Rocky Mountain News; Cats nearby on tot’s hike Cougars spotted during ’99 search; by Joe Garner; 06/14/2003 The Rocky Mountain News; A poignant Father’s Day gift; by Julie Poppen; 06/16/2003 The Coloradoan; Atadero case may prompt negligence inquiry ‘Routine procedure,’ sheriff’s spokeswoman says; by Matthew Benson; 06/17/2003″

From the article “Cats nearby on tot’s hike“ at http://www.rockymountainnews.com/drmn/state/article/0,1299,DRMN_21_2038257,00.html, posted at https://groups.google.com/forum/#!topic/alt.true-crime/j0HvEKykasc by Teresa on 14/06/2003: “As the search progressed, there were reports of seeing signs of cougars, and cats were sighted in the area,” Nelson said. From the article “Lions rarely attack people: Expert uncertain if 3-year-old was victim of cougar” By Gary Gerhardt, Rocky Mountain News, June 14, 2003, posted at https://groups.google.com/forum/#!topic/alt.true-crime/j0HvEKykasc by Teresa on 14/06/2003: “There certainly is nothing to say a lion didn’t kill the boy, but without knowing a whole lot more about it, I think no one would be willing to go out on a limb to make the assertion.” [spoken by Tom Beck, former Colorado Division of Wildlife carnivore specialist.]… “If this cat had kittens, it would be nothing for it to carry the boy uphill for a quarter of a mile,” Beck said.

Again, this refutes the assumption that Jaryd would have been dragged had it been a mountain lion attack.

From the article “Charges eyed in boy’s death: Singles in group were to look after 3-year-old who vanished on hike” By Owen S. Good, Rocky Mountain News June 17, 2003, posted at https://groups.google.com/forum/#!topic/alt.true-crime/j0HvEKykasc by Teresa on 17/06/2003:

“Duggins Wroe, a wildlife biologist from Wyoming, examined the clothing on Friday, the statement said. Wroe said the damage to the shirt’s shoulders and upper arms is consistent with a lion grabbing its prey.”

Related:

Atadero case may prompt negligence inquiry: “Duggins Wroe, a wildlife biologist from Wyoming, has examined clothing found at the scene and concluded that damage to the shoulders and upper arms of a pullover are consistent with that caused by a mountain lion grabbing its prey.”

From the article “No Service For Missing Boy” at http://www.cbsnews.com/news/no-service-for-missing-boy/:

“They found some cougar prints coming down toward his tracks,” said Jaryd’s father, Allyn Atadero. “And where the cougar prints and a little person’s prints come together, the child’s prints disappear.”

Against the Mountain Lion Attack Claim: From the article “Cats nearby on tot’s hike“ at http://www.rockymountainnews.com/drmn/state/article/0,1299,DRMN_21_2038257,00.html, posted at https://groups.google.com/forum/#!topic/alt.true-crime/j0HvEKykasc by Teresa on 14/06/2003: “Animals don’t undress their victims,” said [Dr. Michael] Baden [a New York City-based forensic pathologist], whose resume includes the investigations into the death of President John F. Kennedy and Dr. Martin Luther King Jr. “They don’t take their victims’ feet out of their sneakers.“ and “Atadero said he had been called anonymously by a man who identified himself as a member of the 1999 search team. “He said, ‘Don’t buy into this about a mountain lion,’ ” Atadero said.”

A possible sighting discussed in a podcast:

Possible Sighting in Mesa Verde National Park. Ranger Craig Weston reported spotting a boy matching Jaryd’s description in Mesa Verde National Park with a man. The boy kept holding Ranger Weston’s hand during a tour, which struck Weston as odd. (Source)

From the article “Parker man seeks answers in son’s death: Exactly how 3-year-old boy died remains a mystery” by Chris Michlewicz for Parker Chronicle:

“It doesn’t sound like a mountain lion because there would have been blood everywhere,” Allyn Atadero said.

Regarding this last quote, this Websleuths discussion seems to discount the idea that blood would have been everywhere: http://www.websleuths.com/forums/showthread.php?1739-CO-Jaryd-Atadero-3-Comanche-Peak-2-Oct-1999/page2&s=805ec87f895a64f4b583d9813d655dac

Conclusion:

Based on the above, it appears that the evidence is in favor of a mountain lion attack, although I will keep my eyes open in case I come across anything to the contrary. Sadly, I don’t think absolute certainty can ever be reached in this case.