After 42 hours of searching underwater and along rough terrain without any clues, police say they think the disappearance of Christopher Marks, the 12-year-old Affton boy who went missing Sunday night, may be "nothing more sinister than a sad tragic drowning."

St. Louis County Police Chief Fitch said he is "still holding out hope" for Christopher's discovery, but rescue efforts have turned up no signs that Christopher left the water alive after he was last seen.

"We have every reason to believe that we have checked everything humanly possible," Fitch said. "Just because we checked it doesn't mean he's not there," meaning Christopher could still be in the river or in the woods.

Fitch answered questions at the scene of Christopher's disappearance at 4 p.m. on Tuesday after nearly two full days of search efforts. The massive search-and-rescue efforts may end tonight but an investigation will continue, Fitch said.

Christopher’s family had found a small glimmer of hope in the discovery of a pair of socks near the scene where he disappeared, but Fitch said there is no evidence they were Christopher's.

"The only thing we don't have are the clothes he was wearing when he went in the water," Fitch said. "We don't have any reason to believe we have any clothing that is missing."

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Fitch said police confirmed that the children who gathered on the night of Christopher disappearance were drinking alcohol under the supervision of one adult. 

"It is already a criminal investigation," he said. "That will be given to the prosecutor."

Christopher was last seen around 7:30 p.m. in the Pacific Palisades Conservation Area when he left the group to use a rope swing over the Meramec River. The search for the Rogers Middle School seventh grader drew comments and concern from readers across the country.

Experts said the river's current near the rope swing was not very strong because of the lack of rain. Divers have searched an area the size of a football field in the river and water patrol will continue to search the river for the next two weeks.

Bloodhounds never traced Christopher's scent beyond the edge of the river.

When he left the group, Christopher was barefoot and shirtless, which would make leaving the wildlife area difficult.

Christopher’s great-aunt Donna Sherman, of Sunset Hills, said he and his twin sister, Anna-Marie, have shared a twin telepathy since they were young.

“They were nothing alike, but they felt one another’s pain,” Sherman said. “Anna-Marie felt Chris last night, but today she’s just feeling empty.”

Despite that chilling premonition, Christopher’s family holds out hopes that he simply left or ran away from the scene. He was a Boy Scout and enjoyed swimming. He’d even learned how to survive in the wilderness.

During Monday’s search, the family found an item they hoped was a signal from Christopher: the lip balm his sister gave him the weekend before. Anna-Marie remembered the red, white and blue barrel with a U-Gas brand that family found at the scene, and Sherman said she hoped it proved Christopher left the water after the last time he was found.

Christopher’s grandmother, Lisa Miskimon, posted on Patch to thank the Affton community for their support.

“This is the most horrible thing my family has gone through, and I would like to thank all of the wonderful people in our hometown for all their prayers and all the comments that are posted here,” she said.

For more, here are the articles we've done so far, most recent last:

• Police Search for Missing Affton 12-Year-Old Boy
• Video: Bloodhounds, Divers On Scene to Find Missing Affton Boy
• Search Continues for Missing Boy in Pacific, Lip Balm Found May Be His
• Christopher Marks' Mother Reacts to Son's Disappearance
• Christopher Marks Missing; Friends, Family Community Reacts Online
• Update: No Major New News on Christopher Marks
• Video: $5000 Reward for Information on Missing Christopher Marks
• Fresh Eyes, Dogs Brought in Tuesday to Search for Christopher Marks
• Christopher Marks' Family Told They May Be Able to Search Later
• Video: Police Describe Search and Rescue Efforts for Christopher Marks
• What's Next? Christopher Marks Investigation Wraps Up at Meramec River
• Police: No Clues in Missing Christopher Marks Case; Drowning Possible