Three of the four Mainland Regional High School football players killed in a crash last year tested positive after the accident for chemicals found in marijuana, according to a New Jersey State Police report released Wednesday.

Drug tests showed both tetrahydrocannabinol (THC) and carboxy in the blood of driver Casey Brenner, 17, of Northfield, and passengers Edgar Bozzi, 17, of Somers Point, and Dean Khoury, 15, of Linwood, at levels an expert unaffiliated with the investigation said could lead to impairment.

The accident occurred on Aug. 20, 2011 near southbound exit 38A on the Garden State Parkway.

Brenner's blood had 6.6 nanograms per milliliter of THC and 6.2 of carboxy THC; Bozzi had levels of 30 and 17; and Khoury had levels of 19 and 46, respectively. Toxicology results for Nicholas Conner, 16, of Northfield, were negative.

Richard Saferstein, the former chief chemist at the New Jersey State Police crime lab and now a Mount Laurel-based forensic science consultant, said a concentration of 5 nanograms per milliliter of THC can lead to impairment of motor function.

"It affects your psychophysical behavior, (and) your ability to perform balance and coordination tests properly," he said.

Saferstein said a number of factors, including how often an individual smokes marijuana, can affect THC levels. He said the chemical typically stays in the blood for two to four hours, although it can vary based on the individual's tolerance to the drug. For frequent users, the substance can remain in the blood for as long as 24 hours, he said.

A substance police believed to be marijuana was found at the crash site, then-acting State Police Capt. Frank Davis confirmed last year. Davis has since retired.

State Police said days after the accident that the substance was sent to a lab for testing, but on Wednesday authorities said those results will not be released.

Any record of testing of the substance would be considered a criminal investigatory record and would not be releasable through the Open Public Records Act, State Police Det. Ismael E. Vargas said Wednesday.

The state police toxicology and accident reports were released after an Open Public Records Act request filed by The Press of Atlantic City.

According to a study published this year in the British Medical Journal, the use of marijuana nearly doubled the risk of a serious auto accident among a study group of more than 49,000 people.

Stephen Wallace, senior advisor for policy research and education for the advocacy group Students Against Destructive Decisions, said marijuana can affect a driver's alertness, concentration, perception and coordination, but most people - particularly teens - don't take the risk seriously.

The football players were on their way to a team breakfast in Mays Landing following the last practice of the summer, a long-standing tradition at the high school.

Eight players were in Brenner's 2002 Ford Explorer, including survivors Kyle Beattie, Alex DeNafo, Kenneth Randall and Jacob Smith.

Brenner held a provisional driver's license, which prohibits drivers under age 18 from having more than one passenger, unless the passengers are adults or family members.

Five of the eight vehicle occupants were not wearing seatbelts, according to the investigation's findings.

According to the report, Brenner was traveling southbound in the right lane of the parkway when he came upon slower traffic in the right and left lanes.

Tire marks on the roadway's right and exit lanes indicated that Brenner steered his SUV to the right and entered the exit lane, the report stated. As he approached the guide rail, he then steered the vehicle to the left. The vehicle rotated counter-clockwise on the right shoulder and exit ramp before overturning for 256 feet before coming to rest on its roof.

The report stated that Brenner "failed to maintain the vehicle's position in a lane of travel" and his "overcompensation in steering caused him to lose directional control of the vehicle."

Because Brenner died as a result of his injuries, the report states "there is no cause for further action in this case."

None of the crash victims was autopsied, despite such procedures being common after fatal motor vehicle accidents.

Four of the families filed tort claims last year against the New Jersey Turnpike Authority, the South Jersey Transportation Authority, Atlantic County, Egg Harbor Township and the state.

The tort claims, which are not lawsuits but secure the rights of the families to sue, claim damages of between $1 million and $15 million and allege dangerous conditions were allowed to exist on the roadway.

The report released Wednesday does not address road or weather conditions.

Contact Wallace McKelvey:

609-272-7256

Follow Wallace McKelvey on Twitter @wjmckelvey

Contact Donna Weaver:

609-226-9198

Follow Donna Weaver on Twitter @DonnaKWeaver