Missing Baby Gabriel Johnson: Couple Who Hoped to Adopt Ariz. Baby Took Lie Detector Test

Edecio Martinez

PHOENIX (CBS/AP) Scottsdale couple Jack and Terri Smith, who briefly took care of missing baby Gabriel Johnson, say they know nothing about where the 8-month-old is now.

Arizona police are trying to determine if the baby was given to strangers in San Antonio, as Gabriel's mother Elizabeth Johnson told them, or murdered, as she told the boy's father.

They are also trying to understand what exactly Jack and Terri Smith know. The couple had hoped to adopt Gabriel and police asked them to take a polygraph test last Friday. They also have named them "persons of interest."

"We should be!" Jack Smith told CBS News' "The Early Show." "We were the last people to see Gabriel before he left Arizona. So I was not shocked at all that they named us."

The couple has said they befriended Gabriel's mother Elizabeth Johnson, 23, at an airport and that she wanted to give her son up for adoption. The child briefly stayed with them, but the boy's father, Logan McQueary, did not want to give up parental rights.

Elizabeth Johnson claimed, in an exclusive interview with CBS affiliate KPHO, that she gave the baby away in San Antonio during a road trip.

Police found her abandoned car in San Antonio, but eventually arrested her in Miami, Fla.

She had also sent McQueary a text message saying she had killed the infant.

But police and McQueary say they remain hopeful the child was not harmed.

Terri Smith told "The Early Show" that while Elizabeth Johnson was never affectionate toward Gabriel, she doesn't think the mother could have hurt him.

"She seemed to want the best for him," Terri Smith said.

The Smiths told NBC's "Today Show" that they've shared everything they know with police.

"There's nothing that [Elizabeth Johnson] said that we have not shared with police since day one," Terri Smith said. "She never ever gave specific details. Whether it be a domestic violence shelter, the underground, whether it be a hotel. Whatever it was that she continued to tell me and now I feel like a fool because knowing more stuff now after all the facts have been laid out in front of me, I see that she was lying to us and playing us."

Detectives asked Jack Smith 15 questions about the whereabouts of baby Gabriel in a lie detector test Friday at the Tempe Police Department, according to Phoenix FOX station KSAZ. Detectives told him the test will be sent in for secondary analysis to determine if he was telling the truth.

Police said Sunday that Elizabeth Johnson is being held at the Maricopa County jail on the three felony charges after being extradited from Florida, where she was taken into custody Dec. 30 after failing to show up for a custodial hearing in Phoenix.

Elizabeth Johnson has been charged with kidnapping, child abuse and custodial interference. Police say she's being held on a cash only $1.1 million bond.