VANCOUVER -- Warning: Some of this testimony is graphic.

A Crown prosecutor has laid out disturbing new allegations as the trial begins for two drivers charged in the death of a Brazilian exchange student, including the fact the teen was struck by first one and then the other vehicle.

Fernanda Girotto was crossing at a marked crosswalk on Cariboo Road south of Highway 1 in Burnaby around 7 a.m. on Jan. 17, 2018 when she was struck and killed.

We now know the two drivers charged are each accused of hitting her with their cars, one of them dragging her for dozens of metres.

Prosecutor Geordie Proulx opened the first day of the trial for Paul Oliver Wong, 46 at the time, and Kai Man Cheu, 58 at the time. They're each charged with driving without due care and attention and other motor vehicle act violations.

Proulx alleged Wong hit 14-year-old Girotto with his blue Dodge Dakota pickup truck as she was crossing the intersection on a rainy morning when it was still dark, pulling to the side immediately according to a witness Crown intends to call in the coming days. According to the same witness, another vehicle allegedly driven by Cheu approached the intersection, crossed a double solid line and hit Girotto as she lay in the crosswalk, dragging her under his Toyota Corolla for more than 40 metres before he pulled to the side.

Cheu's lawyer asked that he be excused from the trial unless necessary as he couldn't miss work for the four days the court is expected to be in session. Wong was in the room and looked down and away from the proceedings as the Crown described their theory in the case.

Ambulance paramedic Wayne Mitchell was the first to testify and was visibly upset, describing how he could only see part of a face and a hand from under the bumper of the vehicle when he and his partner asked witnesses where the pedestrian was: "It's embossed in my memory, it was a traumatic scene."

The veteran paramedic says Girotto had "agonal resp," or a gasping reflex, as his partner searched for a pulse, but that they knew the situation "was dire."

He called for a fire rescue truck to lift the vehicle and help the teen. A self-described ex-military member, Mitchell choked back tears as he described doing everything humanly possible to save the teen. He says he called the driver from the crowd to get in the car and back it up to try and free Girotto. Instead, the patient moved with the vehicle and they couldn't remove her.

"We were done. The patient was wedged and we couldn't get access to her chest," said Mitchell. He believes her heart had already stopped before they began trying to free her and that the gasping reflex was due to her brain activity continuing as her body shut down.

In his opening statement, Proulx said an autopsy found it difficult to establish which injuries were caused by which driver, but found Girotto died due to extensive head injuries. Crown told the court it believes those head injuries were caused by the second collision by Cheu.

Crown says 950 evidentiary photographs were taken at the scene and that video from a transit bus will be used in evidence.

Burnaby RCMP Const. Robyn Kaplan was the second witness called and was the first police officer on the scene.

She testified that she knew the case was a fatality and that she took several smartphone photos upon arrival and then began gathering witness names and information.

Kaplan's photos include Girotto's pink gloves; she had been on her way to a day of snow-tubing. Mounties found the exchange student's passport and cellphone.

Const. Didier Pastore was the second Mountie on scene and testified that he spoke with Wong.

"He said, 'I brushed her' with his car," said Pastore, explaining that he wasn't questioning Wong, just reviewing his ID and getting contact information.

In response to queries from the Crown, Pastore testified that neither Wong nor Cheu appeared impaired. Pastore was also the first to go through Girotto's backpack, finding it heavy with school binders. The Portuguese-speaking officer recognized her schoolwork in that language, and then found her Brazilian passport.

Pastore was the one to notify Girotto's sister, Ana, who was also living at a townhome complex nearby. He later met with family members who arrived from Brazil and Brazilian consulate officials.

Pastore was followed on the stand by Const. Clinton Jewell, a member of the Burnaby RCMP’s traffic unit who interviewed the suspects at the scene. Crown played a recording of his 10-minute interview with Wong in court.

Wong described driving down Cariboo and noticing a pedestrian "at the last minute" and jamming the brakes as he swerved to avoid her. Wong describes believing she was wearing dark clothing and a hoodie.

"I think another car had hit her, that was behind me. I called the ambulance right away and started looking for her and couldn’t find her," he said on the recording. "At that point I didn't know if it was male or female."

Jewell: When you struck the pedestrian, did you hear any noise?

Wong: Yes, I heard a thud

Jewell: Any screams or anything?

Wong: No

Jewell: Did you notice knocking anything loose, a backpack or jacket?

Wong: It happened so fast. I went by her, impacted her and pulled over immediately. When I pulled over I couldn't find her. I was running around and couldn't find her.

In the second audio recording, Cheu recounts going to work that morning and seeing a truck parked in the road and passing it, saying, "Suddenly it looks like I got something, hit it. I didn't see anything but I hit it.

"I get out of the car and try to see what I have hitted (sic)," he can be heard saying. "Someone at the bus stop told me I had hitted (sic) a person on the left side of my car."

Jewell clarified with Cheu that he passed on the left side of the pickup truck as he went around it in without stopping.

Jewell: Anything else you would like to say?

Cheu: I really don't know what to say. I really don't expect to have this situation. I never expect (sic) to kill a person by accident.

Proulx noted the level of interest in the case and put special emphasis on a statement describing the two men as working, decent citizens of this country and "like any other Canadian citizen."

The defendants' lawyers entered not guilty pleas for the two charges against Wong and the three charges against Cheu.

They have not yet had the opportunity to make statements, cross-examine or call their own witnesses. The trial is expected to last most of the week and is being heard by Judge David St. Pierre.

Correction: Though Girotto has previously been identified as a 15-year-old, prosecutors have confirmed she was just 14 when she died.

Read back through coverage from CTV News Vancouver's Penny Daflos in court: