Murder suspect Bryan Kohberger's defense team believes one of Kaylee Goncalves, Madison Mogen and Xana Kernodle's surviving roommates may be the key to clearing his name.

Kohberger has been accused of fatally stabbing the three University of Idaho students, as well as Kernodle's boyfriend Ethan Chapin, at an off-campus home in Moscow, Idaho in the early hours of Nov. 13. Two other roommates were asleep during the killings and did not suffer any injuries.

Now, in court documents obtained by E! News on April 25, a criminal investigator working for Kohberger's counsel claimed Bethany Funke—who lived with Goncalves, Mogen and Kernodle at the time of their deaths—has "information material to the charges against Mr. Kohberger." Kohberger's investigator said that some of the information Funke allegedly has is "exculpatory" to the defendant, meaning it could help his defense.

According to the investigator, "Ms. Funke's information is unique to her experiences and cannot be provided by another witness" and that "it is necessary to subpoena this witness because the witness' testimony is material and necessary to this case."

However, an attorney representing Funke argues in a separate filing that the investigator's claims have no merit for the defense to request a subpoena for a preliminary hearing, which has now been set for June 28.

"These statements are conclusory," Funke's attorney wrote in a motion to quash the subpoena. "There is no further information of detail pertaining to substance of the testimony, its materiality or the alleged exculpatory information of Ms. Funke or why it would entertained at a preliminary hearing."

The motion also said that there is no authority to summon a Nevada witness to appear at the Idaho hearing.

"A preliminary hearing is not meant to become a mini-trial due to its limited purpose in deciding probable cause," Funke's lawyer added, arguing that even if Funke did have evidence that could clear Kohberger's name, there is no reason to present it at the June 28 preliminary hearing. 

Kohberger—who was arrested in December and charged with four counts of murder and one count of felony burglary—has yet to enter a plea. Authorities took him into custody after DNA found on the button snap of a knife sheath near Goncalves and Mogen's bodies allegedly matched with DNA sample taken from the trash at the Pennsylvania home of Kohberger's parents, according to an affidavit obtained by E! News in January.

The affidavit also said that the other surviving roommate, only identified as D.M., told investigators she saw a male figure "clad in black clothing and a mask that covered the person's mouth and nose" on the night of the murders.

The figure was described by D.M. as taller than 5'10" with "bushy eyebrows," per the affidavit. D.M. told investigators she stood in a "frozen shock phase" before locking herself in her room.

Kohberger's public defender in Pennsylvania, where the criminology student was arrested, previously said his client believes he'll be exonerated.

"He said this is not him," Jason LaBar told Today on Jan. 3. "He believes he's going to be exonerated. That's what he believes, those were his words."

E! News has reached out to attorneys for Kohberger and Funke, as well as the prosecution in the murder case, for comment but hasn't heard back.