YAKIMA, Wash. — As the search for Dr. Jay Sloop entered its fourth day in Kiev, organizers explained why volunteers focused their efforts on a large urban park in the Ukrainian capital.

The retired obstetrician from Yakima was last seen Tuesday after he left for a morning walk in Kiev, where he had been helping set up a lifestyle center for the Seventh-day Adventist Church.

Surveillance video from Tuesday shows the 77-year-old doctor entering Zamkova Gora, a heavily wooded park in the city center, but not leaving, according to a news release Friday from the church.

Meanwhile, searchers located and reviewed a private camera from the only other entrance to the park, concluding after reviewing hours of data that Sloop did not exit that way either, the news release said.

“While this information has helped to narrow the search, it does not make things easy,” Dr. Fred Hardinge, a colleague of Sloop’s, said in the release. “The park is not flat with manicured lawns as one might assume. Rather, it is a flat-topped hill with very steep sides covered in some rocky outcroppings, trees, brush and bushes and some patches of long, untrimmed grass. A set of steel stairs leads 200-250 feet to the top.”

Jay Wintermeyer, a spokesman for the church at regional headquarters in Spokane, said about 80 church members and 30 students have assisted Kiev police in the search, along with members of the Sloop family.

He said a representative from Adventist Risk Management has been coordinating the search and that military police and Marines from the U.S. Embassy in Kiev have donated their time.

On Saturday, in addition to continuing search efforts at Zamkova Gora, local Adventist churches plan to canvass surrounding areas with photos of the doctor.

“We are doing everything we can to provide all possible help and assistance in the search for Dr. Sloop,” said Victor Alekseenko, Ukraine Adventist Union president.

In a blog post, Greg Sloop disputed rumors that his father’s credit cards were used after his disappearance.

Greg Sloop said his father withdrew a “moderate” sum from an ATM shortly after he left for his walk, but camera footage of the transaction does not show him with anyone or in distress.

“No bank transactions have been attempted ... since he disappeared,” Sloop wrote.

In addition, Sloop said there have been no reports of a kidnapping, adding, “That doesn’t mean it hasn’t happened, but there certainly isn’t any evidence I’m aware of that he was.”

• Chris Bristol can be reached at 509-577-7748 or cbristol@yakimaherald.com.