A federal jury Thursday rejected a former inmate’s efforts to blame his jailers for injuries he sustained after he was exposed as an informant against notorious Philadelphia drug lord Kaboni Savage and brutally beaten in a retaliatory prison attack.

Peter Bistrian, a former financial adviser from Chadds Ford, had sued eight guards at the Federal Detention Center in Philadelphia, saying they blew his cover and ignored his pleas that his life was in danger as a result.

He was beaten in 2006 by one of Savage’s top lieutenants and two other inmates when prison guards placed all four in the same recreation pen in the detention center’s solitary confinement unit.

But the jury of six men and two women took roughly a day to conclude that only two of the guards — J.A. Gibbs and William Jezior — had been aware of the danger Bistrian faced and that neither man had recklessly put him at risk.

The panel’s decision appeared to stun Bistrian and the lawyers and advisers who accompanied him to court each day. They quickly filed out of the courtroom and gathered behind closed doors.

In an email later, his lawyer Richard L. Bazelon said: “We regret that the jury did not render a verdict in favor of Mr. Bistrian.”

Meanwhile, the guards and their attorneys exchanged handshakes and hugs as they filed out of court, discussing where they were headed for celebratory drinks.

Throughout much of the three-week trial, they had pointed to the multiple fraud convictions that had put Bistrian in prison in the first place, and sought to paint him as a con man exaggerating both the extent of his chronic ailments and their cause.

Bistrian “makes up stories for his own advantage,” Sarita Joyce-Moore, attorney for Gibbs, said in her opening statement last week. “It’s what got him into prison, it’s what he did in prison, and he has continued to do it after he was released from prison.”

But while much of the proceedings were dominated by testimony from medical experts debating Bistrian’s current state of health, the trial centered on a drama that played out behind bars 13 years ago at a prison just a block away from where the jurors made their decision.

The circumstances under which Bistrian, a white-collar criminal from the Philadelphia suburbs, came into the orbit of Savage — one of the city’s most violent killers and the only Pennsylvanian on federal death row — had all the trappings of a Hollywood suspense thriller.

Bistrian was working as an orderly in the detention center’s solitary confinement unit in 2006 when an inmate slipped a note under a cell door and asked him to deliver it to Savage, housed in the same cell block.

The former financial adviser agreed, but later offered to secretly share the messages with prison officials who were building a death penalty case against Savage.

Savage, a former boxer who had risen from street-level dealing in Hunting Park to become one of the city’s major cocaine traffickers, was already serving 30 years for drug crimes and was awaiting trial in a racketeering case linking him to a dozen murders — seven of which he had ordered from behind bars.

In fact, it was from the same solitary-confinement unit where he and Bistrian first met that Savage orchestrated his most notorious crime: a 2004 firebombing in North Philadelphia that killed four children and two women related to a witness expected to testify against him.

Bistrian told jurors earlier this month that despite Savage’s record, he agreed to let prison guards photocopy each letter he was passing before he delivered it to Savage or members of his crew. He hoped his cooperation would lead to his own release from solitary confinement, where he had been housed for abusing the prison’s phone system.

But after passing eight to 10 notes — none containing information that aided Savage’s prosecution — Bistrian’s work with investigators was found out. Bistrian’s lawyers maintained that the guards running the operation, Gibbs and Jezior, had accidentally placed a copy of one of the notes into an envelope their client delivered instead of the original.

That tipped off the recipient — Savage lieutenant Steven Northington — to the betrayal, and he spent much of the next several days threatening Bistrian’s life from behind his cell door.

“He was screaming like hell,” Bistrian told jurors earlier this month. “That I was a snake. That I was a rat. That I was going to be effing killed.”

Weeks later, when they were mistakenly placed in the same prison rec-pen, Northington cornered Bistrian and, with two other inmates, pummeled him with fists and feet, and slammed his face into a metal wall before guards could break up the attack.

The beating left Bistrian with a dislocated shoulder, broken fingers, facial and head cuts, and chipped teeth. He testified that he still suffers from longer-term ailments including nerve damage and chronic shoulder and back injuries directly caused by the attack.

“Mr. Bistrian has suffered tremendously as a result,” lawyer Bazelon said during closing arguments Tuesday. “He has steadfastly maintained what took place, the evidence has borne him out, and he has pursued a long road to get here.”

Attorneys for the guards, however, questioned whether Bistrian’s current ailments were caused by Northington’s beating or by an assault four months later — a razor-blade attack by another inmate, which guards were forced to break up by using flash-bang grenades.

Bistrian also has sued the federal government over that incident in a separate trial that opened Thursday before U.S. District Judge Cynthia M. Rufe. He is seeking punitive damages and more than $3 million in medical expenses in that case.