Despite being hit with two tranquilizer darts, a mountain lion managed to elude capture after being found Tuesday evening under the deck of a Casper home.

The animal fled through a gap in a fence and leapt over several other fences before disappearing in an east-side neighborhood sometime about 9 p.m. A search by Wyoming Game and Fish and Casper police failed to find the lion that night.

An additional search Wednesday morning didn't turn up any sign of the animal, and authorities don't plan to look for it again unless another sighting is reported.

"The thing is probably gone," said Justin Binfet, the Game and Fish wildlife biologist who darted the lion. "Hopefully, we will never hear from it again."

The lion was found in the backyard of Nathan and Christi Bekke's Luker Drive home shortly after 7 p.m. on Tuesday. Nathan Bekke is the Star-Tribune's publisher.

The couple's 10-year-old daughter, Vivian, had gone out back to get the family dog and a neighbor's dog for a walk. Her dog, a black Labrador named Jake, bolted under the deck and started barking at something, Nathan Bekke said. The dog then scurried back out and yelped.

The girl went inside and told her mother, who came outside to investigate. She looked under the deck and after seeing the cat, brought the dogs inside and told her husband.

"I went out and took a look, and sure enough it was a mountain lion just laying there," Nathan Bekke said.

The animal was five to six feet back under the deck. Bekke went inside and called Metro Animal Control, 911 and then Game and Fish.

"Our main concern was making sure the kids and the pets in the neighborhood were safe," he said.

The Game and Fish Department arrived at the house shortly before 8:30 p.m. Binfet shot the animal with a tranquilizer dart while it was still under the deck, then darted it a second time when it came out and hid behind some trees and shrubs.

"I wanted to get him put down pretty quick," he said.

The tranquilizer usually takes about 10 to 15 minutes to take full effect. Before that happened, the cat, which Binfet said weighed about 100 pounds, slipped out of the yard through a gap in a fence.

"After that, he jumped a couple of 8-foot vinyl fences," Binfet said.

The cat was last seen about four yards past Bekke's home. At that point, authorities began to warn neighbors and search other yards. Six Casper police officers participated in the effort, said Sgt. Mark Trimble.

Binfet estimated the cat was likely knocked out for a few hours and then left the area. He suspects it came to the neighborhood from Casper Mountain by way of Elkhorn Creek.

"The most likely scenario is this cat was a younger cat that was dispersing from his mother, looking to seek its own territory," he said.

Binfet suggested area residents check their backyards before letting out their children or pets. For the next few days, it wouldn't hurt to keep them inside during the evening or early morning - when mountain lions are most active, he added.

Mountain lions have killed pets in the Garden Creek area, but Binfet said he is unaware of one of the cats attacking a human in the Casper area.

"People don't need to live in fear," he said.

Reach crime reporter Joshua Wolfson at (307) 266-0582 or at josh.wolfson@trib.com.

See a cat?

To report a Mountain Lion sighting, contact Wyoming Game and Fish in Casper at 473-3400. After business hours, contact your local law enforcement agency.