WOBURN, Mass.—Defense attorney John A. Amabile said in court yesterday that he sees potential grounds for a mistrial in the case of accused Kirkland shooter Jabrai Jordan Copney because of an alleged conversation that took place Tuesday between his client and a witness in the case.

Copney and the witness, Blayn Jiggetts, were allegedly placed in the same prison transport and were able to speak to one another while they were being taken from court to jail.

John T. Lu, the presiding judge, has dismissed the jury until Friday while he considers the legal ramifications of the exchange between the two men.

Jiggetts—who made a plea deal with prosecutors in exchange for testifying against Copney—first took the stand Tuesday and was slated to continue when court opened yesterday.

State police interviewed Jiggetts outside of the courtroom yesterday about the alleged conversation in the van. Assistant District Attorney Daniel J. Bennett ’85 then presented a transcript of the 45-minute interview with Lu and Amabile.

“The problem with the conversation [in the van] is that it should never have occurred at all, because these two guys should not have been placed in a transportation together,” Amabile said.

In court, Amabile said that the incident might be sufficient cause to scrap the entire trial, which completed its eighth day yesterday.

“This is a disaster,” he said. “I think we should consider a mistrial at this point and start this thing all over again.”

Matthew H. Feinberg, who represents Aquino, said it was “unbelievable” that Copney and Jiggetts were driven in the same van.

Jiggetts pleaded guilty to the lesser charge of manslaughter in September. In exchange for his testimony against Copney, prosecutors offered Jiggetts a promise of 9 to 12 years in jail, as opposed to the life sentence without parole which Copney faces if convicted of first-degree murder.

On Tuesday, Jiggetts told jurors that he, his longtime friend Jason Aquino, and Copney made plans to steal marijuana at gunpoint from Justin Cosby, the murder victim, and that Copney shot Cosby when the Cambridge resident refused to hand over the drugs.

Because his plea bargain is contingent on his testimony in Copney’s case, Jiggetts has not yet been sentenced.

During the testimony that did occur yesterday, Denise Cosby, the mother of the shooting victim, briefly took the stand.

“Justin was my baby boy,” she said. “He was a mama’s boy. He had a heart of gold.”

While questioning the forensic pathologist who conducted Cosby’s autopsy, Bennett displayed an up-close photograph of the bullet wound in Cosby’s abdomen. Before allowing Bennett to show the image, Lu cautioned jurors that the picture was “gruesome” and that they must not allow their judgement to be swayed by “emotion, passion, prejudice, or sympathy.”

Lu also considered a motion by Amabile regarding the fact that Aquino, who like Jiggetts has pleaded guilty to manslaughter, is not expected to testify in Copney’s trial.

Amabile had requested that Lu give a special instruction to jurors at the conclusion of the case which would authorize them to consider Aquino’s absence as an indication that his testimony—had it been given—would have been unfavorable to the prosecution.

Lu denied the defense’s request, ruling that because Aquino has chosen to utilize his Fifth Amendment right not to testify in a matter in which he could incriminate himself, Aquino is unavailable as a witness.

—Xi Yu contributed reporting to this story.

—Staff writer Julie M. Zauzmer can be reached at jzauzmer@college.harvard.edu.