A court hearing on a request for reduced bail for one of former football star Aaron Hernandez's co-defendants was overshadowed Thursday by the revelation that a man shaping up as the prosecution's star witness has changed a key part of his story.

The hearing centered on Ernest Wallace, described as a de facto uncle and "right-hand man" to Hernandez, and his bid to have his $500,000 bail reduced -- a move that was denied by a judge who concluded that his criminal background and lack of ties to Massachusetts made him a likely candidate to flee the state.

But the attention centered on a man who wasn't in the courtroom: Carlos Ortiz.

Prosecutors have alleged that Wallace and Ortiz were with Hernandez early the morning of June 17, when he is accused of shooting and killing semipro football player Odin Lloyd in a secluded field in North Attleboro, Mass.

And of the trio, only Ortiz has cooperated with investigators -- laying out a detailed story about the murder, some facets of which have been corroborated by surveillance camera footage and cell phone records, according to court documents.

But Assistant District Attorney Patrick O. Bomberg acknowledged during Wallace's bail hearing that Ortiz had recently changed his story on one key detail.

Previously, he had said that Hernandez drove him, Wallace and Lloyd to an industrial park in North Attleboro and parked the car in an area ringed by woods and piles of dirt and other construction material. At that point, Ortiz had insisted, Hernandez, Wallace and Lloyd got out of the car while he stayed behind. He had said that he heard gunshots, and that only Hernandez and Wallace got back in the car, according to court documents.

More recently, Bomberg said in court, Ortiz told investigators that Wallace did not get out of the car. That discrepancy could be key, giving defense attorneys another opening to question Ortiz's credibility if prosecutors put him on the witness stand one day.

And David Meier, an attorney for Wallace, zeroed in on another issue that prosecutors will have to face if they one day put Ortiz on the stand -- the presence of a white towel found on the ground near Lloyd's body. As FOX Sports reported earlier this month , the towel might open the door for defense attorneys to attack Ortiz's credibility by questioning whether he was telling the truth when he insisted he never got out of the car at the murder scene.

Here's why: A surveillance camera image from a gas station, snapped about 90 minutes before Lloyd was killed, showed Ortiz with a light-colored towel draped around his neck.

Hernandez, 23, faces murder and weapons charges in the June 17 killing of Lloyd, whose bullet-riddled body was found in a secluded area about a half-mile from the star player's home. In court documents, prosecutors have laid out a detailed timeline, based on extensive cell phone records, surveillance camera images and statements made by Ortiz.

Prosecutors have alleged that late the night of June 16, Hernandez summoned Ortiz and Wallace from Bristol, Conn., to his home, that the three of them drove the approximately 40 miles to the Dorchester section of Boston and picked up Lloyd, and that they then returned to North Attleboro. There, shortly before 3:30 a.m. on June 17, prosecutors allege that Hernandez shot and killed Lloyd.

The alleged motive? That Hernandez was upset over an incident at a Boston nightclub several days earlier in which Lloyd allegedly talked with people the football player had problems with.

Prosecutors have alleged that Hernandez shot Lloyd with a .45-caliber Glock, which has not been found, and that he also had a .22-caliber pistol in the car with him that day that was later tossed into the brush along a road.

Wallace, 41, faces a charge of being an accessory after the fact in the case.

Ortiz, 27, faces a charge of possession of a weapon by a previous offender and is scheduled to be in court Friday afternoon for a hearing in his case.

On Thursday, attorneys for Wallace argued that his bail, set at $500,000, was excessive, that he had "every reason" to attend future court hearings and asserted that his criminal record and lack of a home and a steady job constituted a "lifestyle" rather than compelling evidence to keep him behind bars.

They asked that bail be lowered to $10,000, but Superior Court Judge E. Susan Garsh denied the request. And along the way, she imposed new requirements on Wallace. In the event he is able to raise the $500,000 to be released, he will be required to stay in Bristol County, to undergo GPS monitoring of his whereabouts, and to be followed closely by probation officers.

In their quest to keep Wallace behind bars, prosecutors detailed more of their evidence in the early morning murder allegedly planned and carried out by Hernandez, a Pro Bowl tight end for the New England Patriots before his arrest. Bomberg filled in some of the gaps in the timeline assembled by prosecutors and divulged other details of the ongoing investigation:

- That Wallace frequently stayed at Hernandez's mansion, and that he often kept a pistol tucked between the mattress and box springs in the bedroom where he slept.

- That Wallace -- who has four aliases and went by the nicknames "Hobo" and "Fish" -- had become close to an aunt and a cousin of Hernandez, helping each of them when they were stricken with cancer.

- That Wallace is suspected of having been with Hernandez in May when he was involved in a dispute outside a nightclub in Providence, R.I., in which several New York Jets fans taunted him. Prosecutors believe Wallace is the man who tossed a .22-caliber pistol under a car -- a gun that was purchased in Florida at the same time as another .22-caliber handgun that was located along a road not far from where Lloyd was killed.

- That a man named Alexander Bradley had previously occupied the position of "the right-hand man of Aaron Hernandez." But that ended in February, when Hernandez allegedly shot him after a dispute at a Florida nightclub. Hernandez has not been charged in that case, but Bradley has filed a civil lawsuit in federal court accusing the former player of shooting him in the face. Bradley has been ordered to testify before a grand jury, but his whereabouts are not known.

- That Hernandez's cousin, Tanya Singleton, drove Wallace to Georgia in the days after Lloyd's murder before buying him a bus ticket that took him to Florida, where he turned himself in after learning there was a warrant out for his arrest. Singleton, 37, remains behind bars on a charge of contempt filed after she refused to testify before a grand jury investigating the case. Prosecutors had previously said they were not sure how Wallace got to Georgia.

- That investigators have obtained more surveillance camera images that purportedly show the Nissan Altima investigators believe was used the night of the murder -- images of it in Boston after Lloyd got into it and from a toll booth along Interstate 90. Prosecutors alleged that Hernandez sped through the toll booth without paying, and an image of the car was captured on film that clearly showed its license plate.

- That on the evening of June 17, when police officers went to Hernandez's house after finding Lloyd's body, his first phone calls were not to his attorney but to Wallace.