New details have emerged about the gun found during the Memorial Day weekend that was linked to the murder of nursing student Holly Bobo. According to a new report, state prosecutors believe the gun was used to kill 20-year-old Bobo, who went missing in 2011.

The trial in the case was delayed last week after authorities said they did not have enough details on the recently discovered weapon. However, court documents reveal the gun is now a "critical piece of evidence."

The gun, found by Tennessee Bureau of Investigation, is listed as an Arminus model HW5, 32 caliber Smith and Wesson long revolver. The gun's cartridges have been tested for blood but no other detail is currently available. Defense attorneys for Zachery Adams, one of the three men accused of kidnapping and killing Bobo, have asked the gun be excluded as evidence, according to the local networks.

Read: Holly Bobo Murder Trial Delay Sparks Reaction Among Local Tennessee Residents

Adams’ trial was scheduled to begin last week, but new evidence in the case forced the delay. The judge granted the motion to continue the trial until September.

Meanwhile, Nashville's News Channel 5 reported Bobo's parents have called to testify in her murder case, along with Adam's grandfather Dick Adams.

Ahead of the trial, five witnesses — Victor Dinsmore, Michael Alexander, Jason Kilzer, Shayne Austin and Jason Wayne Autry — were granted federal or state immunity in the case last week. 

Defense attorneys requested for all rape charges to be dropped saying, "It is undisputed that no evidence regarding the alleged rape of Ms. Bobo will be presented to the jury."

Bobo disappeared in April 2011 in the woods near her West Tennessee home. Her brother told investigators he saw his sister go into the woods near their home with a man dressed in camouflage. Her remains were later found near Adams’ home.

“He actually had an arm holding her,” John Mehr of the Tennessee Bureau of Investigation said at the time. “So we feel she knew she was in fear of her life, so she was compliant with his commands.”

Adams’ attorney argued there was no DNA evidence linking his client to Bobo’s death, according to CBS-affiliate WTVF. Adams’ mother, Cindy Adams, also expressed doubts over the fact that forensic evidence in the case remained sealed.

Read: New Evidence In Case Forces Delay

“They would have found DNA in that house,” she told NBC-affiliate WMC-TV in May. “They would have found hair in that house. They would have found a fingernail. They would have found something that placed Holly in that house. There’s no chemical cleanup in that house. There’s nothing that ever indicated Holly has been in that house.”

Adams was arrested and charged in March 2014 with especially aggravated kidnapping and first-degree felony murder. His brother and Autry were also charged and all three pleaded not guilty.