Bruce Jenner Confessed He's Taking Heavy Doses Of Hormones Ahead Of Gender Reassignment Surgery

Bruce Jenner was taking hormones at the time of the fatal car crash ahead of a planned gender reassignment surgery; did the hormones contribute to the car crash?

"There is no suggestion that the hormones were a contributing factor in the tragic accident," a Jenner source told RadarOnline.com.

The former Olympic gold medalist, involved in the tragic accident Saturday in Malibu, broke his silence on the incident Sunday, saying in a statement that his "heartfelt and deepest sympathies go out to the family and loved ones, and to all of those who were involved or injured in this terrible accident."

After passing field sobriety tests at the scene of the accident, Bruce voluntarily agreed to submit to a blood test at a local hospital as part of the investigation into the cause of the accident that left an elderly woman dead.

Los Angeles County Sheriff's deputies accompanied Bruce to the hospital for the blood test. (He wasn't taken into custody or arrested.)

During the blood draw, Bruce was asked if he was taking any medication and said that "he was taking very low dosage of hormones that his doctor had prescribed," a source told RadarOnline.com. "Bruce has nothing to hide, and was very cooperative with cops, and appreciated their professionalism.

"During the entire process Bruce was obviously very, very shocked and inquiring about the other victims -- this has been a total nightmare for him, and Bruce is taking it very, very hard."

Bruce had revealed to taking the hormones so he could grow breasts, to look more feminine before his planned gender reassignment surgery​, the source said.

Jenner was driving his Escalade and was towing a trailer with an all-terrain vehicle when he ran into the white Lexus from behind, Los Angeles County Sheriff's Department Sgt. Philip Brooks said. The Lexus spun into oncoming traffic and was hit by a Hummer H2 and the driver of the Lexus was killed at the scene. The pileup started when a Prius stopped in the northbound lanes on Pacific Coast Highway, according to the Sheriff's Department.​

Bruce and the driver of the Prius could be facing involuntary manslaughter charges as a result of the fatality. (Bruce could also be cited for following too closely behind the Lexus.)

The deadly accident sent five people to the hospital, including several small children. Early reports speculated the crash was caused by Jenner attempting to flee from paparazzi. However, police said that didn't appear to be a contributing factor of the accident.

Jenner and the female driver of the Prius are indeed "being investigated for potential involuntary manslaughter," the source told Radar. "If the driver of the Prius was attempting to make an illegal U-turn or was using a cell phone to talk or text, which is illegal while driving, that person could absolutely be charged.

"The driver of the Hummer likely wouldn't face any charges because the Lexus was pushed into their lane, and couldn't make any defensive moves to avoid the crash. The fact that Bruce was towing a vehicle, also contributed to the force of the Lexus being hit."

Pictures taken just moments before the crash reveal Bruce was smoking a cigarette and didn't appear to be texting or talking on his cell phone.

Police will be conducting an accident reconstruction investigation, though it'll be difficult because hours after the crash, a suspected drunk driver plowed thru the barricades, striking two of the vehicles.

For now, Bruce's kids, including Brody and Brandon, "are hunkering down with their dad -- they are a very close-knit family, and will do whatever is needed to help him at this very sad and tragic time," the source added.