It all came down to one troubled star witness.

Legal experts said the case against former Patriots star Aaron Hernandez rose and fell with Alexander Bradley, a convicted felon and Hernandez’s marijuana supplier, who testified for the prosecution that he watched Hernandez pull the trigger — and who defense attorneys argued was the real killer.

“The verdict does not surprise me,’’ said Martin W. Healy, chief legal counsel to the Massachusetts Bar Association. “Given Bradley’s checkered past, that seemed to overshadow anything he was trying to convey to the jury about Hernandez’s involvement.’’

After six days of deliberations, the jury found Hernandez, 27, not guilty of killing Daniel de Abreu and Safiro Furtado in a drive-by shooting in the South End in the early-morning hours of July 16, 2012. They also acquitted him of witness intimidation in the shooting of Bradley in Florida in 2013. He was convicted on just one charge, illegal possession of a firearm.

Prosecutors had argued that Hernandez became enraged after de Abreu bumped into him inside Cure Lounge and spilled a drink on the athlete. Bradley testified that he was driving Hernandez’s Toyota 4Runner when the two men left the club, and Hernandez reached across him and fired into their BMW. Though there were three other passengers in the BMW that night, none could identify Hernandez, leaving Bradley’s word to stand alone.

But Bradley came with baggage. He is currently jailed in Connecticut for an unrelated club shooting, and he testified for prosecutors under an immunity deal. He texted his lawyer fretting that he’d be charged with perjury if he told “the truth’’ in a related case. His initial description of how Hernandez discarded the weapon did not fit with where it ultimately turned up, and though he described the drink-spilling incident, no video or other witnesses ever turned up.

“If you say, ‘We’re the state. We’re asking you to rely on this guy — this is our guy. He is the one we want you to believe A to Z, every detail,’ that’s a big ask,’’ said attorney Rosanna Cavallaro, a professor of law at Suffolk University.

For Hernandez trial-watchers outside the courtroom, Cavallaro said, the facts may look very different than they did to the jury inside. Hernandez has already been convicted in another murder, of Odin L. Lloyd in June 2013. Officials have told the Globe that Lloyd may have been killed in part because he knew Hernandez killed de Abreu and Furtado. None of that information was presented to the jury in the double murder trial.

Instead, jurors heard a narrative that relied heavily on Bradley’s credibility. Cavallaro said she thought the verdict was more a reflection of the jury’s inability to believe the prosecution theory beyond a reasonable doubt than an indication that they thought Hernandez was innocent.

“It was up to the jury to decide who pulled the trigger, obviously it was one of them,’’ said defense attorney Stephen J. Weymouth. “Maybe they just couldn’t decide which one.’’

Ronald Sullivan, one of Hernandez’s lawyers, said the acquittal will have no direct impact on his appeal in the earlier murder case, adding that Hernandez’s celebrity status “worked adverse to his interests’’ in the earlier trial.

“We hope that the public now sees Aaron for who he is,’’ Sullivan said. “A very good young man who happened to hang out with a really bad guy in Alexander Bradley.’’

In the recent trial, experts agreed that the defense put on a strong case, with devastating cross-examinations. Healy called it “one of the best defenses I’ve seen in this jurisdiction in a long time.’’

But outside observers also praised prosecutors, who they said did the best they could with what they had. The case took years to solve, and may never have been closed at all without the murder of Lloyd a year later.

“There aren’t any options here,’’ said attorney Timothy M. Burke, who spent 10 years as a prosecutor, trying about 25 murder cases, and now runs a private practice in Needham. Bradley was the witness the prosecutors were stuck with, he said.

“It’s not like you can go to the witness pool and say, ‘Let’s find somebody who is unimpeachable, and who was returning from church services when they witnessed the shooting,’ ’’ Burke said. “Real life doesn’t happen that way.’’

Travis Andersen of the Globe staff contributed to this report. Evan Allen can be reached at evan.allen @globe.com.