In an update issued Tuesday, the Lehigh County District Attorney's Office said "no obvious nor apparent causes of death" have been found.
The investigation is ongoing pending toxicology tests.
The vehicle belonging to Eleanor Camacho, 58, was located at 4:12 p.m. Sunday in the area of Lumber and Turner streets.
Camacho, who was a mother of four children and expecting her first grandchild, was found dead inside her 2015 Buick Enclave.
"It's scary because I don't know if it's a murder or if she died naturally," said Margarita Barreto, who lives on the block where the car was found.
She says she remembers seeing the car Friday and, as the weekend went on, she thought it was strange it was still there.
"I just knew something was off because normally when their business hours are closed, nobody's supposed to be parked there," Barreto said.
Camacho was last seen in the parking lot of her apartment on the 1100 block of South Cedar Crest Boulevard in nearby Salisbury Township on Thursday evening.
"She was very caring, willing to take care of people," said Kimberly Kurdes, who used to work with Camacho.
Kurdes says Eleanor was so proud of her kids.
"She talked about them all the time. I mean, I never met them in person but I feel like I know each of them," said Kurdes about Camacho's family.
She said this has been a painful ordeal.
"That was the hardest thing was feeling helpless, that I couldn't do anything for her," Kurdes sad. "We were just hoping for the best, that she was going to come out of this."
Neighbors in the area say there was a massive police scene on Sunday.
"I saw detectives here. They had the whole thing blocked off with the yellow ribbon. I never saw something in my life like that," said Freddie Hernandez.
Kurdes says something just doesn't add up, adding that her friend was looking forward to so much in her life.
"She was so excited to be a grandmother for the first time and I just pray for them and my heart breaks for them," she said.
Anyone with any information is asked to call 610-437-7753.