(CNN) -- Shaken police officers in Houston, Texas, provided details Thursday in the death of a 12-year-old Texas boy whose burned body was found in a drainage ditch.
Jonathan Foster was last seen December 24. The medical examiner has not released the cause of death.
Mona Yvette Nelson, 44, a maintenance worker and an acquaintance of the boy's family, was arrested Wednesday and the Harris County District Attorney's Office has accepted capital murder charges, said spokesman Kese Smith of the Houston Police Department.
Police credit a security video taken by a business in helping to crack the case, homicide Capt. David Gott told reporters.
Police said the business video was taken around 6 p.m. that day.
The video, he said, shows someone pulling up in a silver truck, unloading a body and placing it in a ditch about five miles from the apartment at which Jonathan lived.
"She has still not confessed, still has not said that she murdered Jonathan Foster," Gott said of Nelson. "But she did admit that it was her truck and that she was there at that ditch and she is that person in that video putting that body in the ditch."
The suspect met Jonathan's stepfather two weeks before he vanished, according to CNN Houston affiliate KHOU.
Investigators said Nelson, the only suspect, made a "self-serving statement" that places her with Jonathan, but she has not admitted to killing the boy.
Jonathan's mother was away at work when he disappeared on the afternoon of December 24. The boy's stepfather saw him around 1:45 p.m., Gott said. Jonathan called his mother's workplace and spoke with someone who relayed a message to her. She came home around 2 p.m. to find Jonathan was gone.
Officers at the apartment complex were in the process of trying to talk with Nelson, who they understood had talked with Jonathan around 12:30 p.m., Gott said. They had received a video image of the truck and noticed it was similar to Nelson's, he added.
No accelerants were found on the body, Gott said. While he would not go into any details, he did say welding torches were found at the suspect's home, along with other evidence authorities said she tried to conceal. They believe the body was burned at Nelson's house.
Detective Michael Miller said officers are uncertain about a motive, but he described the suspect he helped interview as showing "an absolute lack of remorse" for Jonathan's killing.
Nelson, who was being held without bail Thursday, was friends with the roommate of Jonathan's mother, police said.
Jonathan was a happy, red-haired and well-liked boy, Miller said. "It's an absolute tragedy that cannot be put into words."
CNN's Divina Mims contributed to this report.