A lawsuit filed by the mother of a Surrey teen who died in 2014 after a violent assault says a delayed ambulance response is to blame for her son's death.

A civil suit filed against the province, Ministry of Health and the 911 dispatcher alleges that the life of 15-year-old Dario Bartoli may have been saved had his case been assigned a higher priority. Instead, his injuries were categorized as non-life-threatening, and it took more than 20 minutes for paramedics to arrive on scene.

Bartoli died on Dec. 13, 2014 after he and a friend were attacked by a group of four or five people in Bakerview Park. Police arrived at the scene and called for paramedics to rush the boy to hospital, but were put on hold for nearly three minutes, according to the lawsuit.

When no ambulances arrived, police had to call back and again ask for assistance. RCMP were put on hold again when they called six minutes later, this time for 36 seconds. Police called Emergency Health Services again, when the ambulance had not arrived 18 minutes after their initial call requesting paramedics, the lawsuit says.

Police were called at 2:43 a.m., and made the first call to EHS at approximately 2:46, court documents say. The ambulance arrived at about 3:10 a.m., 24 minutes from the first call, or 21 minutes taking into account the three minutes the RCMP dispatch centre was put on hold.

Bartoli went into cardiac arrest due to blood loss while being loaded into the ambulance, according to the statement of facts provided in the suit.

The vehicle left the scene at 3:21 a.m., and arrived at Peace Arch Hospital four minutes later. The teen underwent multiple procedures while in hospital, but died shortly after 10 a.m.

No one has been charged in Bartoli's death.

Ambulance response timeline

Bartoli's mother, Junko Iida, claims that her son's life could have been saved, were it not for the lengthy delay.

In court documents obtained by CTV News, she claims the 911 dispatcher erroneously entered information that led to the call being assigned as a Code 2, instead of the more urgent Code 3.

The coding system is used to prioritize resources based on severity of the case. Codes are generated by a software system based on the information entered by dispatchers, and a Code 3 is used for cases involving heavy bleeding, obstructed breathing, loss of consciousness, severe head pain and other serious ailments.

Under Code 3, ambulances are allowed to use sirens and lights, so they can get to the scene faster. Code 2 is meant for non-life-threatening conditions, and paramedics driving the ambulance obey traffic signals and other rules of the road without sirens and lights, according to the lawsuit's statement of facts.

The lawsuit alleges that an ambulance could have been at the scene 11 minutes earlier -- a figure based on average ambulance response time of nine minutes and 15 seconds -- had Bartoli's condition been properly entered into the code-assigning system by the dispatcher.

Despite numerous calls from police regarding the urgency of Bartoli's condition, including at least four specific requests for a Code 3 ambulance, the code in the dispatch system remained at 2.

The dispatcher also inputted that there was one assault victim instead of two. The suit claims that if she had included the second victim, the code would have automatically been upgraded.

Paramedics read Code 2 on their ambulance's on-board computer system, and heard Code 3 from RCMP on the radio, and became confused, further delaying response time, the lawsuit says.

It claims that Bartoli's death was "caused and/or contributed to by the negligence" of the 911 dispatcher.

"The defendant… knew or ought to have known that by assigning Code 2 as opposed to a Code 3 ambulance unit to the scene it would result in harm to Dario," the civil suit states.

The suit filed against the dispatcher also names the provincial government and the Ministry of Health as defendants. Emergency Health Services is expected to file a statement of defense in the months ahead.

The lawsuit claims that the province is "vicariously liable" in the case for the dispatcher's actions, as well as several other particulars including failure to ensure dispatchers are adequately supervised, have proper training and follow EHS policies.

As a result of Bartoli's death, his mother has suffered loss of guidance and companionship, support, household assistance and care, the lawsuit states.

None of the allegations have been proven in court.

In addition to the court documents, CTV News has obtained new details from a letter written by the Surrey fire chief to the Provincial Health Services Authority. The January 2015 letter was first obtained in July, but several details were redacted.

Although some sections remain redacted, some of the previously censored details have been made public, including that Chief Len Garis had been told by other members of his staff that Bartoli's case was not the first instance of error made by the B.C. Ambulance Service.

He said he'd been informed that BCAS dispatchers are making decisions about whether to notify first responders based solely on their "remote (over the phone) interpretation of the patient condition."

Garis wrote that it is "imperative" that fire, police and ambulance services have consistent systems in place so that they can be improved as a whole.

"With dynamic decision making, occurring in BCAS dispatch, this detracts from what other emergency services expect and rely upon for determining their processes and policies," the letter says.

Later in the letter, Garis wrote that RCMP expected a Code 3 response in Bartoli's case, but that the requested code was not passed on to the fire service.

"This created angst and anxiety for the people who rely on the system to operate as expected," he wrote.

Garis's letter prompted an extensive review of ambulance response times, according to PHSA executive vice-president Linda Lupini. In the summer, she told CTV that the review highlighted "some things we could improve" and generated internal discussions.

"We believe we've improved the process significantly since then," she said.

PHSA is now working more closely with Surrey Fire, and have added three ambulances to the city's fleet.

Officials don't know whether a faster response time would have made a difference for Bartoli, Lupini said, but the case was taken very seriously.

With a report from CTV Vancouver's Scott Roberts