(CNN) A new witness has come forward in the death of a 19-year-old fraternity pledge at Clemson University , leading his family to believe they may finally be closer to knowing what happened to Tucker Hipps before he died.

New court documents in the family's $25 million lawsuit allege the political science major was forced to walk along a narrow bridge railing in a hazing incident before he fell to his death.

Hipps died nearly a year ago, as he was pledging Sigma Phi Epsilon at Clemson. For months, the criminal investigation into his death has been at a standstill as officials were unable to determine exactly what happened in the early hours of September 22. That may change with the motion filed in court this week.

"It does answer some questions," Hipps' mother said. "[It] connects some of the dots. There's still some dots missing. ... We want the whole truth."

The county solicitor, however, says there are "multiple issues" with the new witness, and his information will not advance the criminal case. "The sheriff's department thoroughly investigated and interviewed the alleged witness. There will be no criminal charges resulting from this witness' statements," Oconee County Solicitor Chrissy Adams told CNN.

Hipps' family believes the university, the fraternity and three of its members are to blame for the death, and tried to cover it up after the fact. They are suing in South Carolina state court, and the new allegation is part of a request to amend their lawsuit with the new details.

Tucker Hipps was a sophomore at Clemson.

One of the fraternity brothers named in the suit is Samuel Carney, son of U.S. Rep. John Carney, D-Delaware. He is accused of organizing the event. The suit also names two other brothers, Thomas Carter King and Campbell T. Starr, and says the three have "all been deceptive and failed to be forthcoming with police," and that Starr deleted text messages and switched phone numbers after Hipps' death.

Hipps' body was found floating in Lake Hartwell hours after he died. Until now, there was no official account of how he ended up in the lake. According to the lawsuit, a tradition existed of requiring, pressuring or forcing pledges to jump off one of the bridges over Lake Hartwell and swim to shore.

The lawsuit also says the pledges were forced to participate in a predawn run, a hazing ritual, despite the fact that early-morning runs had been banned by the national Sigma Phi Epsilon fraternity, and violated Clemson's hazing policy. A text that went out to the pledges said "wear dark clothes so [we're] not spotted." A brother texted Hipps, telling him to bring McDonald's breakfast for 30 people. But when he showed up without it, there was a confrontation.

In the new documents, the proposed amended lawsuit says that, according to an unnamed witness, three fraternity members "forced Tucker to get onto the narrow railing along the bridge and walk some distance of the bridge on top of the railing." It goes on to say, "Tucker slipped from the railing and caught the railing under his arms .... tried to climb back onto the bridge unassisted ... lost his grip on the bridge and fell headfirst into the water below, striking his head on the rocks in the shallow water."

After Tucker fell, "King shined the flashlight on his cell phone into the dark waters below looking for Tucker," but no one tried to rescue him, according to the suit, which also says they waited at least three hours before looking for him, and didn't call campus police for help until seven hours later. The lawsuit also says the brothers stalled Hipps' girlfriend when she asked where he was; they said Hipps had been spotted in the library.

An autopsy later found he had injuries to his arms and legs, and his head injury was consistent with a headfirst fall.

The county solicitor said the new witness "...describes seeing several kids on the bridge as he is going over the bridge ... and one of them was on the railing. He's not quite sure of the time, or the day."

In a statement, Adams goes on to say, "He describes the students as laughing and having a good time," which would indicate that there was no force or hazing involved. He said the students he described were wearing orange, when Hipps and the fraternity brothers were wearing dark clothes.

In addition, the witness drove on the bridge on his way to a gym at Clemson, but the sheriff's department says records show he did not go to the gym that day. Adams added, "During the interview with the Oconee County Sheriff's Office this witness appears to be coaching himself on the video when he is alone in the interview room."

Hipps' parents are outraged that county officials have dismissed the new witness, and in a statement said, "While we believe that counsel making public comment on the credibility or substance of witness statements is both inappropriate and prejudicial, we are compelled by recent events to respond. We could not disagree more with Ms. Adams' opinions regarding the credibility of the new witness or the witness' statements.

"We have sincere hope that the people of this community will refrain from drawing conclusions until all the evidence has been presented."

Carney, King and Starr have responded to the original suit, denying the substance of the allegations, pinning the negligence on Hipps and asking that the suit be dismissed. So have the university and the national chapter of the fraternity. None of the defendants in the case has responded yet to the proposed amended lawsuit.

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King's attorney wrote in a court filing that he denies the allegation there was a confrontation over a lack of breakfast.

Starr's attorneys deny he witnessed anyone go over any bridge over Lake Hartwell, and says he only changed his cell phone number because he was being harassed by media.

In a statement released to media last year, Carney's family said they had urged their son to cooperate. His attorneys said in their response to the lawsuit that there is no "allegation that Sam Carney saw or had anything to do with how Tucker Hipps ended up in the water under the bridge that morning."

Clemson, which had several incidents with fraternities leading up to Hipps' death, was planning to suspend fraternity activities starting at 5:30 p.m. the day Tucker died. According to records obtained from the university, there was talk of walking back the moratorium out of concern for media attention. But after Hipps' death, all functions were suspended, and officials said it was because of several troubling incidents that had been reported, not just Hipps' death.

Hipps' mother, Cindy Hipps, said if she and her husband had known about the previous violations, they would have pulled Tucker out of pledging. As it was, they had concerns about the process, but say they were swayed by the university's orientation, which highlighted only good things about fraternities.

"After that class I felt better about it," Cindy Hipps said. "They said kids in frats have better time-management skills .... those kids had higher grade-point averages. All the things a mother wants to hear, I heard. I convinced his dad to let him do it. Never once did I even feel like the child would be harmed in any way."

Hipps said her son -- with his contagious smile and big bright eyes -- was the kind of person who took homeless people to lunch, even though he was just a college kid with little money.

He had chosen Sig Ep because he had plans to go to law school after graduation and believed the fraternity might help him get internships.

Plus, she said, he was an only child who was always looking to be around others.

"That's part of the reason he wanted to be in the fraternity, so he had a brotherhood." Hipps' mother said, adding, "His dad and I miss him so terribly. He still is the first thing and the last thing we think about every day and he is just terribly missed."