TOWN OF BELOIT, Wis. (WKBT/WISC) -

A relative of the boy who was found safe Friday morning was charged with his abduction, authorities said. 

U.S. Attorney for the Western District of Wisconsin John Vaudreuil said 31-year-old Kristen R. Smith, of Denver, was charged Friday afternoon with kidnapping newborn Kayden Powell from a home in the town of Beloit. Smith is Kayden's aunt, the half-sister of Kayden's mother, Brianna Marshall.

Eighteen-year-old Marshall, of Beloit, reported the newborn missing at 4:30 a.m. Thursday. The West Branch, Iowa, chief of police found the baby at about 10:15 a.m. Friday outside a gas station, 29 hours after he'd gone missing and 180 miles away.

The complaint alleged that Smith took Kayden from the Beloit home and transported him across state lines to Iowa.

According to the criminal complaint filed Friday, police spoke with Smith over the phone minutes after the baby was reported stolen. Smith was at an Iowa gas station, where a local police met with her. Smith was arrested Thursday in Iowa on an unrelated warrant out of Texas. Smith is being held at the Cedar County Jail in Tipton, Iowa.

The complaint said Smith told officers that Marshall and Kayden's father, 23-year-old Bruce Powell, were planning to move to Colorado to live with Smith. Smith denied knowledge of Kayden's whereabouts, the complaint alleged. She later said Kayden's parents gave him away to a family member in Chicago and denied involvement in the baby's disappearance.

Police found baby clothes, a car seat and stroller in Smith's car Friday morning, but no children. Emails and Facebook posts were also found that said Smith gave birth Wednesday, the complaint alleged. A prosthetic pregnancy belly was also in Smith's car.

The BP gas station on Highway 80 in West Branch where Kayden was found is about 500 yards from the gas station where Smith initially made contact with police.

The complaint said after Kayden was found, Smith admitted to taking the newborn from her sister's home in Beloit and she had placed him behind the gas station in Iowa. She gave police a hand-drawn map of where the baby was found, the complaint said.

Vaudreuil's office said Smith faces a maximum penalty of life in federal prison if convicted. Bail for Smith would be set at $15,000, Vaudreuil told News 3. Authorities are expected to extradite Smith to Madison in about a week.

Vaudreuil said he believed Kayden was left outdoors in a plastic tote overnight.

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Officials say they have not identified suspects or made any arrests in the disappearance of 5-day-old Kayden Powell, who went missing from a town of Beloit home early Thursday morning.

Town of Beloit Police Chief Steve Kopp said 18-year-old Brianna Marshall woke up at a home in the 800 block of Homeland Court about 4:30 a.m. Thursday to find her child missing from his bassinet. Marshall immediately called police.

Marshall, a School District of Beloit student, does not live at the home where her son went missing, police told News 8's sister station in Madison, WISC-TV.

Kayden Powell is African-American, 20 inches long, weighs 6 pounds and has brown hair and brown eyes.

Police cannot issue an Amber Alert because there are no suspects or vehicle descriptions.

Police said there was no forced entry to the home and the parents are being cooperative. The home is being processed for physical evidence, and 40 officers and investigators are talking to family and friends.

Kayden's father is 23-year-old Bruce Powell, Kopp said.

Rock County Sheriff Bob Spoden said the sheriff’s office has committed its entire detective bureau and investigation unit to the case.

“This is a very serious situation we’re encountering,” Spoden said.

Police have made contact with six people who were at the home the night before Kayden disappeared.

Kopp said a person police wanted to talk to was arrested on a warrant unrelated to Kayden's abduction. Kristen Smith, of West Branch, Iowa, was taken into custody. Smith is Brianna Marshall's half-sister, police said.

"We are focusing our attention on locating the child right now," said Leonard Peace with the Federal Bureau of Investigation. "There is no indication that there is a greater concern for public safety."

FBI agents were dispatched from their Milwaukee office Thursday morning to help with the situation, Peace said.