A local civil-rights activist who supported then clashed with the Aaroné Thompson family said he will testify Wednesday before the grand jury investigating the young girl's disappearance.

"I said whatever I could do to help find that baby, I will," Alvertis Simmons said Monday, recounting his conversation with Aurora police.

Spokespersons for the police and Arapahoe County District Attorney's Office said they could not comment on grand jury proceedings.

The story was first reported Monday by CBS 4 News' Rick Salinger.

Aaron Thompson called Aurora police Nov. 14 to say his daughter had run away from home. But officers soon called off the search and said she may have been killed up to a year and a half earlier. Police then named Thompson and his live-in girlfriend, Shely Lowe, "persons of interest."

Lowe died in May, shortly after the DA's office said it was turning the case over to the grand jury. Aaroné, who would be 7 if she were still alive, has never been found.

Simmons organized a prayer vigil for Aaroné and told Monday how he helped find two high-profile defense attorneys to work with Lowe and Thompson.

Lowe and Thompson promised to speak further with police in exchange for his help in getting the attorneys, according to Simmons. But he does not believe they ever did.

"I know I should have been more astute than that because lawyers will make you lawyer up," Simmons said.

Simmons later told Thompson Aaroné's body had been found - which turned out to be false. But Simmons, a father of three girls, said he was disturbed by Thomp-son's reaction.

"He just sat there stoically, like, 'We busted now,' " Simmons said Monday.

Sam Riddle, a Thompson family friend, questioned what Simmons could tell the grand jury.

"I don't know what the hell he could add," Riddle said. "This is not about supposition."

Simmons said he was called Friday by Detective Randy Hansen, the lead Aaroné investigator, and told he had been subpoenaed by the grand jury. Simmons said he agreed to accept the subpoena but wanted to meet in a public place instead of the police station.

The two met Friday at a gas station in Aurora, Simmons said.

Simmons said he will testify at 1:30 p.m. Wednesday.

"Maybe it's helpful, and maybe it's not," he said. "I don't know."