When a 4-year-old boy was found alone -- naked, sooty and crying -- in a burning Minneapolis home in January, authorities sought to find out, among other things, where his mother was.

It turns she was at a casino, according to a felony charge filed this week.

The mother, Yeng Moua, 44, was charged Wednesday with child endangerment. She was charged by summons and remains free pending a court appearance that has yet to be scheduled.

The little boy was treated for minor burns from the fire, which broke out on Jan. 3 in the upper unit of a duplex in the 3400 block of Penn Avenue N., the criminal complaint read. The child's three older siblings -- ages 7, 10 and 11 -- had gone to school that morning and left the child alone, the complaint continued.

According to the complaint, on that January day, a resident of the duplex's lower level heard fire alarms blaring from the unit above for at least 20 minutes.

When the neighbor went upstairs and knocked on the door, the child opened the door and appeared to be afraid, crying and with "soot marks on his body leading up to his nose," the complaint read.

The neighbor tried to put out the fire in the kitchen with a bucket of water and a towel, then took the boy down to his home and called 911. He cleaned up the child and clothed him.

On Friday afternoon, that neighbor declined to comment about the fire but did say that Moua had recently moved from the duplex.

Moua, the boy's only parent, told authorities that she left home the previous midnight for a casino while all four of her children were sleeping.

She said she returned to the home at 3:30 p.m. that day to find there had been a fire and her 4-year-old no longer there.

Moua acknowledged that the boy has a penchant for starting fires and that she knew he would be left alone when her other children went to school that morning.

A Hennepin County child-protection hearing on the case is scheduled for May 3.

Staff writer Nicole Norfleet contributed to this report. Paul Walsh • 612-673-4482