The jury deliberating the fate of former Casper Dr. Shakeel Kahn -- accused of running a multi-state prescription drug conspiracy -- must start over after a juror was released from jury service on Thursday and replaced with an alternate, according to U.S. District Court Judge Alan Johnson.

With this change, it's possible the jury may not decide the verdict with its 23 questions until next week further lengthening the trial that started four weeks ago with jury selection.

"Because [alternate] Juror Number 19 has not participated in deliberations to this point, the jury must begin its deliberations anew," Johnson wrote in a supplemental jury instruction filed late Thursday afternoon.

"Disregard entirely all previous deliberations occurring before now and consider the evidence as if the prior deliberations had never occurred. You should wipe the slate clean and start anew in evaluating the evidence and answering the questions posed to you in the Verdict Form," he wrote.

No reason was given for why the previous juror was dismissed.

The five-man, seven-woman jury received the case in federal court in Casper on Wednesday morning after a nearly four-week trial with thousands of exhibits, and scores of hours of testimony from former patients, expert medical witnesses and Kahn himself.

The jury deliberated until Wednesday evening and resumed Thursday morning.

During that time, the jury sent messages to Johnson asking about what some of the counts were referring to, and asked why one count was not in the jury instructions.

Johnson responded to the first message, saying the evidence was closed and the jury needed to look at the third superseding indictment for the charges about "dispensing of oxycodone" and "dispensing of oxycodone and aid and abet."

In his second response, Johnson said that count is not for the jury's consideration. According to the indictment, it was about the "unlawful use of a communication facility" dealing with a conversation between former defendants Lyn Kahn, wife of Shakeel Kahn, and Paul Beland. Shakeel Kahn was not a part of that conversation and so was not indicted on that count, according to the indictment.

Lyn Kahn and Beland pleaded guilty before the trial and in exchange for their pleas testified for the prosecution.

Shakeel Kahn is charged with 21 counts in a 23-count indictment including conspiracy to distribute oxycodone and other drugs resulting in death, operating a continuing criminal enterprise, having a firearm during a drug trafficking crime, unlawful use of communication device, and money laundering.

If convicted on all counts, he faces 25 years to life imprisonment.

Kahn has asserted that his treatment of pain is aggressive, but it is not illegal; and those who testified against him lied.

His brother Nabeel Kahn is charged with conspiracy to distribute oxycodone and other drugs resulting in death, and brandishing a firearm during a federal drug trafficking crime.

If convicted on those counts, he faces at least 27 years imprisonment.