A 4-year-old boy died after he was left alone for hours in a hot SUV with the window cracked while his father worked an event in downtown St. Paul, according to charges filed Monday.

Kristopher A. Taylor, 26, of Apple Valley, was charged in Ramsey County District Court with second-degree manslaughter in connection with the boy's death Saturday. Taylor remains jailed in lieu of $25,000 bail ahead of a court appearance Friday.

Taylor, working at the Minnesota Monthly 8th Annual Grillfest at CHS Field, parked his SUV at the home ballpark of the St. Paul Saints in a spot that was "entirely exposed" to the elements, the criminal complaint read.

The boy's mother left the boy in Taylor's care around 2:30 a.m. Friday while she went to work, the complaint noted. Taylor's son was identified by a close friend of the family as Riley Taylor, the couple's only child.

Allison McGill, a friend of Taylor's mother for the past 10 years, described Taylor "an amazing kid, a straight-A student who works so hard and loved Riley so much."

Taylor said he last checked on Riley about 11:30 a.m. Saturday and returned about 5:15 p.m. after work to find the boy "stiff" and unresponsive, the complaint continued. Taylor then took the boy to Regions Hospital, where he was pronounced dead.

The temperature over the time period ranged from 70 degrees under partly cloudy skies around noon to 64 and mostly cloudy conditions as of 5 p.m., according to the National Weather Service.

The Medical Examiner's Office ruled preliminarily that Riley died from hyperthermia.

Taylor told police he lowered one window roughly one-quarter to one-half inch for the boy, according to the complaint. He said he gave Riley a handheld video game to occupy himself.

He said he didn't think it was too hot to leave the boy in the SUV, and did the same about a year ago with no problems. However, the complaint continued, Taylor said he left one window down entirely in the earlier instance.

A longtime national advocacy group said 52 children died inside vehicles from excessive heat in 2018, the deadliest year on record in the United States.

KidsAndCars.org has been lobbying for the federal government to require technology in all vehicles that would alert a caretaker about children inadvertently being left in a car.

"A vehicle acts like a greenhouse, heating up to deadly temperatures within minutes, even on a mild day," the group said in a statement released soon after Taylor was charged. "Children have died from heatstroke in cars on days where it was less than 60 degrees outside.

"Contrary to popular belief, cracking the windows does nothing to decrease the maximum temperature reached inside a vehicle. Additionally, a child's body temperature rises 3 to 5 times faster than an adult's."

Taylor offered varying versions events to police, with the time Riley was alone in the car changing with each account, the complaint said:

At first, he told an off-duty officer at Regions Hospital that the boy was with him during the event, became tired about 2:45 p.m. and wanted to go back to the SUV. Taylor said he returned to the vehicle at 5:15 p.m. to find Riley unresponsive.

After being arrested, Taylor initially told police the boy came into CHS Field with him. When work slowed a bit for Taylor at a time not disclosed in the complaint, he returned Riley to the SUV for a nap.

Two co-workers told police that Taylor never left during his shift, and that prompted police to question him again.

This time he said he had to bring Riley to work because he couldn't find anyone to watch the boy and last checked on him about 11:30 a.m.

"Taylor said he didn't think it was that hot," the charging document said.