The man accused in the disappearance of 4-year-old Maleah Davis is the key to finding her body, but he's not talking, Police Chief Art Acevedo said Thursday during a plea for tips.

According to Houston's top cop, Harris County Jail inmate Derion Vence, 26, has refused to elaborate on Maleah's whereabouts since May 4 when he reported her missing.

"We strongly believe he knows where she's at," Acevedo said during a news conference.

As for everything else Vence has divulged, the chief dismissed it as "a tall-tale."

The alleged fabrication stems from when Vence, who was engaged to Maleah's mother, was tasked from April 30 to May 3 with caring for the child. He told investigators that three men knocked him unconscious and abducted the girl while they were on their way to pick up Maleah's mother at Bush Intercontinental Airport.

He was arrested and charged on May 11 with tampering with evidence, in this case a human corpse, after police found traces of decomposition in his car and blood linked to the girl's DNA in their apartment.

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"The evidence shows that she's been murdered," Acevedo said, marking the first time that local authorities have publicly floated the notion that Maleah is no longer alive.

"I can sit here and say we're going to find her alive, but I'd be lying," Acevedo continued. "She deserves to be found. She deserves to be recovered. She deserves to have a proper burial."

The lack of cooperation has extended beyond Vence, HPD Executive Assistant Chief Matt Slinkard also said during the news conference.

"We are not receiving the level of cooperation that we need from anybody involved," Slinkard said.

Acevedo urged the public to continue sharing tips, adding that Houston Crime Stoppers has already pledged $5,000 for information leading to Maleah's discovery. The reward later ballooned to $15,000 on Thursday night as the chief tweeted that Maleah's maternal aunt and uncle would supply another $10,000.

Texas EquuSearch crews have scoured a large swath of land since Maleah's disappearance, including the fields near the site of the alleged abduction and the thick vegetation near Vence's Alief area apartment.

Searchers later trekked 30 miles south of Houston to Rosharon where Vence previously had a mail route. The search has since been called off pending new leads.

Acevedo compared the search for Maleah to the 2014 disappearance of a toddler boy in Austin whose body was found buried in a wooded area.

"I was there when we found him, when the FBI found his body in a carpet under an inch — a foot at most — of dirt," said Acevedo, who was chief of Austin's police department at the time.

The discovery brought law enforcement officials to tears, Acevedo continued.

"There wasn't a dry eye."

Anyone with information is urged to call Houston Crime Stoppers at 713-222-TIPS (8477).

jay.jordan@chron.com

nicole.hensley@chron.com