The mother of a 3-month-old baby found inside a St. Louis County apartment building was killed by a gunshot wound to the head, according to police.

Autopsy results released about 12:30 p.m. Thursday listed the cause of death for Ebony Jackson-Shelton as "a gunshot wound to the head," said Leah Freeman, public information specialist for the St. Louis Metropolitan Police Department.

The reward for information leading to an arrest and conviction in connection with the crime is up to $1,000, Freeman said.

Rickey Collins, chief of the Pine Lawn Police Department, has been collecting money on the corner of Natural Bridge and Jennings Station Road for two days along with some of his men. He hopes that the reward money will help find whoever is responsible for Jackson-Shelton's death, he said.

Pine Lawn is not involved in the investigation but Collins said when he heard the story, he was moved to do something.

Freeman said the investigation is now in the hands of the St. Louis Police Department.

Police found her body in the trunk of Jackson-Shelton's white 2004 Mitsubishi Gallant, which was located in the 4400 block of Elmbank Avenue in north St. Louis.

Jackson-Shelton's 3-month old son, Donovan Prom, was found unharmed in a car seat at an apartment complex in Breckenridge Hills, Mo., at 5 a.m. Friday. Police have been searching for the infant's mother since the infant was discovered.