Neighborhood watch volunteer George Zimmerman shot Trayvon Martin from a very close range, according to documents a Florida prosecutor released Thursday that indicate a hand-to-hand struggle occurred before the teenager was killed.

A lab report, based on an examination of the two sweatshirts Martin was wearing, found holes and gunshot residue consistent with a “contact shot,” meaning the gun was pressed against Martin’s chest. An autopsy report said that the gunshot wound indicated he was shot from an “intermediate range,” which experts say is between one and 18 inches away.

The reports, among nearly 200 pages of newly released information, add to the fragmented portrait of what happened the night of Feb. 26 in Sanford, Fla., when Zimmerman shot the unarmed black 17-year-old, provoking nationwide debates over racial profiling and self-defense laws.

It is unclear how the new documents might bolster or undermine the state’s case against Zimmerman, who has a Peruvian mother and a white father.

The information includes laboratory reports that show Martin’s blood had traces of THC, a chemical that is found in marijuana. Toxicology reports also found blood under Martin’s fingernails, Zimmerman’s blood on Martin’s sweatshirt and Martin’s blood on Zimmerman’s red jacket.

Martin’s autopsy report shows that he had a small abrasion on his left ring finger, which might support Zimmerman’s account that Martin was punching him or the idea that Martin was fighting for his life. A photo of Zimmerman shows he had a bloody nose on the night of the clash; a paramedic reported that he had a one-inch laceration on his head and a forehead abrasion. The injuries, said the paramedic, produced “minor bleeding.”

A report from the Sanford police’s lead investigator, Christopher Serino, states that he thought there was probable cause to charge Zimmerman with manslaughter.

The new documents include crime-scene photographs, interviews with witnesses and medical reports, and provide the most detailed look yet at the evidence that prosecutors are using to build their case against Zimmerman, who was charged last month with second-degree murder.

He has said that Martin attacked him and that he shot the unarmed teenager in self-defense. Martin was walking home to the house where he was staying inside the gated Retreat at Twin Lakes — where Zimmerman also lived — when the incident occurred. Prosecutors allege that Zimmerman followed him and provoked a confrontation.

The bullet from Zimmerman’s 9mm Kel Tec semiautomatic entered Martin’s body on the left side of his chest, struck his heart and one of his lungs, and remained in his body, according to medical reports.

The documents include information that points to what some have characterized as a sloppy and incomplete police investigation, which initially resulted in no charges being filed. That sparked rallies across the county calling for Zimmerman’s arrest.

“It’s a mess,” said a state investigator in one interview in the documents, explaining that he was working on the case apart from the Sanford Police Department.

Witness accounts indicate that in some cases, officers seemed to have rushed to judgment about one of the most critical questions in the case: who was screaming in the last seconds before the gunshot rang out.

One distraught witness, who said she regretted not helping the person yelling outside her window, said in her handwritten statement that an investigator tried to comfort her by saying that the cries for help “were not the person who died.”

A police report also concluded that the voice screaming in the background of a recorded 911 call placed by a resident was Zimmerman, “who was apparently yelling for help as he was being battered by Trayvon Martin.”

But an FBI audio analysis of that crucial call could not determine whether it was Martin or Zimmerman who was screaming, because of the poor quality of the recording and the “extreme emotional state” of the person screaming, an FBI report said.

Also included in the reports is an account of a meeting between an investigator and Tracy Martin two days after his son was shot. The investigator played the 911 call to Martin and asked him whether the voice calling for help was his son’s.

“Mr. Martin, clearly emotionally impacted by the recording, quietly responded no,” the report said.

But in the days and weeks after the shooting, Tracy Martin and Sybrina Fulton, the teenager’s mother, said they had no doubt that the screams were those of their son. In an interview with an investigator, Zimmerman’s father said, “That is absolutely, positively George Zimmerman yelling for help.”

The documents include new details about what witnesses said they heard and saw that dark, rainy night outside their townhouse windows. One witness told police that he heard someone saying, “I’ve got a gun. I’ve got a gun.”

Another said she heard “arguing” coming from the walkway behind her residence. Yet another woman said she looked out her sliding glass door and saw “two men chasing each other, a fistfight between the two men” and then heard the gunshot, according to the police report.

The documents were released by special prosecutor Angela B. Corey, who was appointed by Gov. Rick Scott (R) to investigate the case after a clamor arose over the lack of charges in the weeks after the shooting.

Zimmerman’s attorney, Mark O’Mara, received the documents Monday as part of the discovery phase of the case.

“Please remember and understand that it is inappropriate for us to comment on particular pieces of evidence,” the lawyer said in a statement posted to the Web site he set up for Zimmerman.

Amid the clinical findings and the formal police reports are more personal inventories, artifacts of the two lives that intersected that night: Zimmerman’s size 38Buffalo Jeans and brown boots; Martin’s black cellphone with a heart decal; $40.15 found in Martin’s pocket.

Staff researcher Julie Tate contributed to this report.