Johnny Johnson was driving 115 mph before accident that killed Matthew Hersl in front of City Hall.

The driver of a vehicle that crashed outside City Hall and killed a city worker was traveling up to 115 mph before he entered downtown streets followed by a state trooper, according to a police report that for the first time details the investigation into the April crash.

Johnny Johnson's car crashed through a light pole, hit 45-year-old finance employee Matthew Hersl and broke a tree before overturning, the report said. Police found heroin rocks, a burnt spoon, a smoking pipe and a syringe inside the vehicle. Johnson was arrested six days later.

Hersl's family released a copy of the state police report Tuesday as members urged city prosecutors to bring Johnson to trial. Relatives and supporters gathered at the spot where a tree was planted in Hersl's memory and said prosecutors had informed them that they are considering a plea offer.

Johnson, 44, of West Baltimore, faces charges of vehicular manslaughter and drug offenses that together carry a maximum sentence of 21 years in prison. Family members said the case is too strong not to be placed before jurors.

"We want to go to court," Hersl's brother, Stephen Hersl, 51, told reporters. "We don't want a plea deal."

State police could not be reached for comment on the report, which details the circumstances surrounding the crash, including the involvement of a state trooper who encountered Johnson's vehicle on Interstate 83.

The family released the document through attorney Steven D. Silverman, whom they have retained to investigate whether the trooper improperly engaged in a pursuit within city limits.

State police commanders were concerned as well, according to the investigator, Sgt. Jon McGee, who wrote that he was pulled into a meeting with top brass the day after the crash and heard "general questions and concerns regarding the fact that [the trooper] followed the Acura into Baltimore City and whether or not the events leading up to the crash was a chase or not."

While McGee's investigation does not reach a conclusion on that aspect, his analysis of surveillance cameras and the trooper's in-car video recording show the trooper was about eight seconds behind Johnson's Acura, did not have his siren on and had stopped at a red light before the crash. The officer told investigators he "was not chasing the vehicle," police wrote.

The trooper, identified only as "Z. Mills," said he was driving through downtown on his way to the Essex barracks when the black Acura drove up from behind and nearly hit his vehicle. He told investigators the driver slammed on the brakes when he saw Mills' cruiser, causing the Acura's tires to smoke and making the car wobble.

Mills said he activated the rear lights on his cruiser to warn the driver to slow down, and the Acura followed him as he crossed all four lanes. Suddenly, he said, the Acura made a hard turn onto the Pleasant Street exit. Mills followed as the driver ran a red light on Holliday Street, according to the report, but the trooper stopped at the light.

Mills "saw the vehicle veer left towards the sidewalk [on Lexington Street] and it looked like the vehicle was 'going to lose it,' and the next thing he saw was a big puff of smoke and heard a loud bang," McGee wrote in the report.

Some witnesses said the trooper was following the speeding vehicle, and some said they did not see the trooper until several seconds after the crash, when Johnson struggled to flee the scene.

A time analysis of city surveillance cameras showed that Mills' vehicle crossed the intersection at Holliday and Saratoga streets eight seconds behind the Acura. The trooper was one of the first on the scene who took Johnson to the ground and placed him under arrest.

Johnson, who had been fired from his job as a receptionist at the Maryland Community Health Initiative the morning of the crash, according to the report, is scheduled for trial Dec. 12. His attorney, Maureen Rowland, did not reply to a request for comment.

The charge of vehicular manslaughter carries a maximum sentence of 10 years; the other charges could bring 11 years.

Baltimore State's Attorney Gregg L. Bernstein declined to comment on the case but said the penalties for vehicular manslaughter are "woefully inadequate" and need to be strengthened to hold deadly drivers more accountable.

"Our duty to the victim's family and to the city is to pursue justice by mounting a thorough investigation and an aggressive prosecution," Bernstein said in a statement. "Justice also requires me to refrain from commenting on pending cases, although I will say that my thoughts are with Mr. Hersl's family."

Bernstein called Hersl's death a "horrible tragedy" that stole "a man who was both cherished by his loved ones and dedicated to making Baltimore a better place."

Hersl's family is the latest to say that city police or prosecutors do not communicate with them or consider their concerns when investigating a case.