DAVISON TOWNSHIP (WWJ/AP) – Law enforcement officers, others trained in search and rescue operations and bloodhounds scoured a Flint-area park Wednesday for a 9-year-old autistic boy missing since the weekend.

Volunteers were asked to step aside as professionals searched a 5-mile radius in and around the Lake Callis Recreation Complex in Genesee County’s Davison Township for Omarion Humphrey.

READ MORE: Pistons Drop Rematch With Lakers

Davison Township Police Chief Rick Freeman says as many as 80 K-9 search teams scoured a five-mile radius around the Lake Callis Recreation Center, with 800 law enforcement and search and rescue personnel behind them.

It’s the first time since the search started that “true bloodhounds” were being used in the heavily wooded area, according to Freeman.

Omarion has been missing since Saturday evening following a gathering at the park with his foster family

Area residents are being asked to search their backyards and pools — anywhere where Omarion could be hiding.  And police say people who visited Callis Lake Park should check and re-check their vehicles and campers for the boy.

“We’re going into neighborhoods; doing knock and talks on residences — encouraging people to helps us look…and we’ll have some standard questions that we’ll be asking folks we come across also,” Freeman said.

Meanwhile, searchers are learning more about autism, he told The Flint Journal.

Authorities have kept the park’s splash pad, pavilion and ball fields lit at night and music has been playing in hopes of coaxing Omarion from hiding if the boy still is in the area.

“We’ve used techniques that you almost think would be silly in some investigations,” Freeman said. “The experts are telling us these are little things – anything we can grab at that might attract his attention.”

But the boy’s birth mother has told WJRT-TV that she no longer believes Omarion is in or near the park.

READ MORE: Michigan rises to No. 2

“I think somebody took him,” Khisha Humphrey said. “I don’t think he’s in the wooded area at all.”

Humphrey said Omarion is one 11 of her children taken earlier this year by the state. The state said she didn’t have adequate housing, Humphrey said.

Police have no evidence Omarion was abducted, but that’s not being ruled out, Freeman said.

“We went into this with an open mind, as we should on any investigation,” he said.

Relatives of the boy have been questioned, and their homes and vehicles searched.

“Not only have we had the army of searchers out that are very visible, we’ve had what I’ll call an army of investigators on the family side of this,” Freeman said.

The boy  is about 4-feet tall and 70 pounds with black hair and brown eyes. He was last seen wearing only black shorts with a thin, red stripe — no shirt and no shoes.

Authorities say Omarion may not speak but answers to the name “Mars.”

Anyone who thinks they’ve seen this missing child should immediately call 911. Anyone with other information is urged to contact police at 810-732-4720.

MORE NEWS: Chaotic Finish Leaves Lions At 0-10-1

TM and © Copyright 2015 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2015 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.