The jury in Jodi Arias' first-degree murder trial failed to reach a unanimous decision in the third phase of her near six-month trial on Thursday.

The failure to come to an agreement on whether Arias should have been sentenced to life in prison or given the death penalty led to the judge declaring it a mistrial.

Family members of Arias' murder victim, her ex-lover Travis Alexander, sobbed uncontrollably as the members of the jury confirmed one by one that they failed to reach a unanimous decision. The announcement was so emotional that some of the jurors were seen mouthing the words "I'm so sorry" to Alexander's family members.

The ruling of a mistrial means that the decisions the jury made in the first two phases of the trial still stands - the first degree murder conviction and the ruling that Alexander was killed in a "cruel manner"- but the third phase, the sentencing phase, may be re-tried with a new jury.

Judge Sherry Stephens announced in the Maricopa County courtroom that the new proceedings will begin July 18. If the proceedings rule in favor of no re-trial of the sentence phase, then Arias will serve life in prison. If the penalty phase is re-tried and the new jury cannot reach a unanimous decision, then the final decision for the sentence options will be left up to the judge.

The ruling of a mistrial was declared two days after Arias asked the jury to not give her the death penalty and her defense attorneys and prosecutors gave their closing arguments.

Arias was found guilty of murder in the first-degree on May 8 and the jury reached a "cruel manner" verdict on May 15. "Cruel manner" is when a victim suffered physical and or mental pain, according to Arizona law.

According to the autopsy report, Arias stabbed her victim almost 30 times, slit his throat from ear to ear and shot him in the forehead. The report showed that some of Alexander's stab wounds included cuts on his hands which were caused when he tried to prevent Arias from stabbing him repeatedly.

Watch the judge declare a mistrial in Jodi Arias' first-degree murder trial here.

Tags: Jodi Arias