Newly enhanced surveillance video appears to back the theory that a 4-year-old boy may have wandered out onto the street on his own and was struck by a vehicle Sunday night.

Detectives have been questioning whether Marterrance Albury actually rolled out of the SUV as a 911 caller first believed or if the boy wandered into the street and was the victim of a hit-and-run on Florida Avenue near 109th Avenue.

Video obtained from a nearby business depicts a small child running on the sidewalk and into the roadway. The dark green, possibly black, Ford Expedition continues traveling southbound without stopping.

It is not clear if the driver committed a crime or if this is a tragic accident, police said.

A witness says that at around 9:45 p.m. Sunday, Albury was seen tumbling out of the back passenger door of a Expedition that was heading south on N Florida Avenue near 109th Avenue. A witness who'd been driving behind the Expedition told police he saw Marterrance land on his head before the vehicle's back tires rolled over him.

The Expedition continued south, leaving Marterrance injured in the road. The witness called 911, and Marterrance was taken to St. Joseph's Hospital, where he later died, police said.

Family members said Albury's 17-year-old brother Sam was supposed to be watching the toddler Sunday night at their Parkview Apartments home but may have been distracted by a video game. The teen told police he has no idea how the child got out of the apartment or how he ended up in the street.

Sam had been put in charge of watching Marterrance by his mother, Johntea L. Williams, 36, while she went out with a friend. The family lives in an apartment on the 10000 block of Brittany Lane, adjacent to where the incident happened.

"If I didn’t feel like he wasn’t dependable I would have never left him my child with him. That’s his brother. He loves him so much," said Johntea Williams.

Rosemary Williams, the boys' grandmother said Sam is heartbroken, just like the rest of the family.

"I’ve talked to Sam," Rosemary Williams said. "Sam is so emotional and broke right now he really can’t talk. Right now we know no more than you all know. We want to know what happened."

Police also want to know who was driving the SUV and what led up to the 4-year-old being in the street.

In addition to Tampa police, the Department of Children and Families is also investigating.

The agency investigated the family twice in the past but the cases (that did not involve Marterrance Albury) were closed.

Anyone with information is asked to call Tampa police at 813-276-3200 or Crime Stoppers at 1-800-873-TIPS (8477), go to www.crimestopperstb.com or text “CSTB” plus the tip to CRIMES (274637).