He then drove her car to North Philadelphia, police say, where he abandoned her body in a lot and left her belongings - packed into the car in anticipation of her move - strewn about her.
Then, according to police sources, Jakson drove the car to South Philadelphia and set it on fire around 2:20 a.m. Monday - badly burning both his arms in the process, and leaving his cell phone behind.
At 4:30 a.m., a fire investigator responded to the University of Pennsylvania hospital for a report of a man suffering from burns - Jakson, Bell said.
First Deputy Commissioner Richard Ross said Jakson initially told the investigator that he had been burned during a fight.
Later that day, Bell said, the investigator saw a news report on Araujo's killing and realized the car on fire had been registered to someone with the same last name.
The investigator called the homicide unit, Bell said, and Jakson was brought in for questioning - his arms still bandaged from the burns.
Investigators also used Jakson's cell phone records to trace him to the crime, police sources said.
Detectives and police officers on Wednesday searched the West Philadelphia home where Jakson and Araujo both lived.
Jakson's mother, reached by telephone, declined to comment Wednesday.
Efforts to reach Araujo's family were unsuccessful.
Jakson was charged with murder, robbery, theft and related charges.
Bell said Jakson is known to law enforcement. He was arrested twice as a juvenile for auto theft and robbery. In 2011, he was charged with receiving stolen property and unauthorized use of a motor vehicle but was found not guilty.
Araujo, who has roots in New York and Oklahoma City, had recently graduated with a degree in fashion marketing. She was set to start a new job at a local hotel in the coming weeks, homicide Capt. James Clark said Tuesday.
"She was a very nice young lady, very successful, had a lot of good things in her future," he said.