(CNN) -- For the first time, newly released search warrant documents show why authorities began investigating former NFL star Aaron Hernandez as a possible suspect in an unsolved Boston double homicide in July 2012.
The warrant and accompanying eight-page affidavit do not state whether Hernandez is believed to have been directly involved in the drive-by shooting, nor is there a suggested motive.
But as CNN has previously reported, a grand jury has been looking into whether Hernandez played a role in the drive-by shooting, according to law enforcement sources. No charges have been filed and authorities have not commented publicly on the investigation.
That 2012 shooting is separate from a 2013 killing in which Hernandez is charged and awaiting trial.
Hernandez, 23, was indicted for first-degree murder and weapons charges by a different grand jury in August , 2013, in the shooting death of his friend Odin Lloyd. Hernandez has pleaded not guilty.
The former New England Patriots' tight end was arrested in late June, 10 days after authorities say Lloyd, a 27-year-old semi-pro football player, was killed in North Attleborough, Massachusetts.
The search warrant and affidavit reveal that an anonymous tipster contacted police days after Lloyd's execution-style shooting to talk about the separate drive-by shooting the previous year.
A man who was identified as a security supervisor at a nightclub in Boston tipped off authorities that he "had knowledge the two incidents were related," according to the newly released search warrant, which was executed in December.
When a dispatcher asked how the tipster knew about two incidents that occurred nearly a year apart, the caller said, "Someone accidentally spilled the beans on me," according to the warrant's affidavit, which didn't elaborate on that point.
In the affidavit, a detective wrote that the man had "very specific details" about a suspicious vehicle with Rhode Island license plates, and information about the date, time, and place of the 2012 double homicide. The man told detectives his source for the information was a patron of the nightclub who he knew as "B" or "G."
The affidavit said that, before the tipster's call, Boston detectives involved in the 2012 drive-by investigation were watching TV news reports when they heard that Hernandez was a possible suspect in Odin Lloyd's murder. The detectives remembered seeing Hernandez on the nightclub's surveillance video screened in July, 2012.
These two disparate pieces of information prompted police to take a closer look at surveillance videos already examined, including those from another nightclub, called Cure, and a nearby parking garage, according to the court documents.
After going back to the surveillance tapes, authorities recognized Hernandez driving a silver Toyota 4Runner into a parking garage just after midnight on July 16, 2012, the warrant states. About a half hour later, Hernandez is seen with another man later identified as Alexander Bradley following the soon-to-be victims of the double homicide and two other men as they entered the nightclub Cure about midnight, the affidavit adds.
Ten minutes later, "after consuming two drinks," Hernandez is seen leaving Cure with Bradley. the document says.
At about 2:20 a.m., a video reviewed by police showed the same silver SUV looping around the block "at a very slow rate of speed" after the victims leave the club and enter a parking garage, the documents show.
A short time later, police said, victims Daniel Abreu and Safiro Furtado, were fatally shot in a 2003 BMW. Two others in the car survived. There is no video of the shooting.
One of the survivors told police that just before the gunfire, an SUV was stopped next to them at a red light.
According to the documents, another witness came forward on July 19, 2012, days after the double homicide. A man told police he and a friend saw a Nissan or Toyota SUV with Rhode Island plates pull next to his car, then run a red light the night of the double homicide. The driver was described as a "light-skinned Hispanic man with short hair," the documents state.
At the next intersection, the witness said, the same SUV pulled next to a BMW. Then, according to the warrant, the witness heard six quick gunshots, pulled up to the BMW, and saw the wounded men inside. He called police.
At the time, Boston police asked the public to be on the lookout for a light-colored or silver SUV but were unable to locate the vehicle with Rhode Island plates.
That changed after Lloyd's murder when the focus on Hernandez as a possible suspect in Lloyd's death led police to his uncle's home in Bristol, Connecticut.
Inside the uncle's garage, authorities discovered a silver Toyota 4Runner with Rhode Island license plates, according to sources. As CNN has previously reported, law enforcement sources believe it is the same vehicle described in the unsolved double homicide in Boston.
The warrant confirms the vehicle is the same SUV given to Hernandez by a dealership return for promoting its business.
Police have since recovered a .38 caliber handgun they've identified as the murder weapon in the unsolved double homicide in Boston. But police have not established a connection between the gun and Hernandez.
Alexander Bradley, the man identified by the document and law enforcement sources as being with Hernandez in the club the night of the double homicide, is suing Hernandez for allegedly shooting him in the face last year in Florida after they left a Miami strip club.
According to law enforcement sources, Bradley has testified before separate grand juries investigating the unsolved Boston homicides and Lloyd's murder.
However, before Bradley appeared before the grand juries, he was jailed in Connecticut because he failed to show up despite a subpoena.
The new court documents state while in jail, Bradley's calls were routinely recorded. According to the documents, when a correction's officer listened to the conversations -- five of them in October, 2013 -- he heard Bradley "discussing details of the Boston homicide investigation."
The affidavit doesn't reveal who he was talking to or exactly what was said.
Bradley's attorney did not respond to a CNN call on Thursday. He previously has declined to address any details about his client beyond acknowledging the lawsuit.