( CNN ) -- A Tennessee juror 's laudatory Facebook message to a medical examiner during a murder trial could nullify the jury 's conviction of William Darelle Smith , the state 's Supreme Court ruled Wednesday . The high court did not immediately throw out the first-degree murder conviction of Smith , who was sentenced to life in prison in 2010 . But in concluding the trial judge erred upon learning of the juror 's social networking communication with a key prosecution witness , state justices unanimously decided a new trial may be necessary unless the state proves the juror should n't have been disqualified . `` If , for any reason , the trial court is unable to conduct a full and fair hearing with regard to juror ( Glenn Scott ) Mitchell 's improper extrajudicial communication with Dr. Lewis , then the trial court shall grant Mr. Smith a new trial , '' the Supreme Court ruled , referring to the juror by name , as well as Dr. Adele Lewis , the medical examiner who testified . The Davidson County , Tennessee , District Attorney 's Office did not have an immediate reaction Wednesday to the ruling . Smith 's public defender declined to comment . A county grand jury indicted Smith in the death of Zurisaday Villanueva , whose body was found June 4 , 2007 , off a Nashville road along with two .9 millimeter shell casings . The two had been living together , according to court documents . Smith went on trial in March 2010 . After the jury was set , jurors were told by the judge they `` should not talk with any witnesses , defendants or attorneys involved in this case . '' Testimony followed , including from Smith 's cousin , who said the defendant told her a pistol `` went off '' while he and Villanueva were arguing and again when Smith was trying to move Villanueva 's body . The prosecution also presented evidence indicating Villanueva 's blood was in an automobile driven by Smith and owned by his father . The second-to-last person to testify for the prosecution was Lewis , a Vanderbilt-trained assistant medical examiner . She conducted an autopsy on Villanueva and classified her death as a homicide , saying Villanueva was shot in the chest and the back of the head . The next day , about an hour after the jury began deliberating on Smith 's fate , Lewis e-mailed presiding Judge Seth Norman that she had been contacted via Facebook by a juror who was an acquaintance . `` A-dele ! ! '' the juror wrote , according to the e-mail included in the state Supreme Court ruling . `` I thought you did a great job today on the witness stand . ... I was in the jury ... not sure if you recognized me or not ! ! You really explained things so great ! ! '' Lewis responded by saying she thought she recognized the juror , then warned of `` a risk of a mistrial if that gets out . '' The juror wrote back that he was aware of the risk , saying he had n't mentioned he knew Lewis . The first time the juror-witness communication came up in official court proceedings was after the verdict was delivered , but before sentencing . That 's when public defender Mike Engle asked if the court asked the juror about the exchange , to which the judge replied , `` No , I 'm satisfied with the communication that I have gotten with Dr. Lewis with regard to this matter . '' Smith later asked for a new trial , in part because the defense was n't allowed to question the juror . The trial court ruled against him , as did a state appeals court that characterized the Facebook communication as `` mere interactions '' and noted it is up to the court to decide if a juror is impartial . The state Supreme Court 's ruling on Wednesday overruled those decisions . Stressing that `` the public 's confidence in the fairness of the system '' requires that all jurors be held `` accountable to the highest standards of conduct , '' the justices said the trial court should have taken `` steps to assure that the juror has not been exposed to extraneous information or has not been improperly influenced . '' In Smith 's trial , this could have been addressed at a hearing at that time or a `` full-scale investigation , '' the court said . Neither occurred , leading the state Supreme Court to send the case back to the trial court for a hearing on the Facebook communication and the jurors ' impartiality . Conversations between jurors and people involved in a case have long been forbidden in state law . But the court admits that technology -- including the Internet , which allows jurors to conduct research and more readily communicate -- has complicated matters . `` Even though technology has made it easier for jurors to communicate with third parties and has made these communications more difficult to detect , our pre-Internet precedents provide appropriate ( guidelines ) , '' the ruling states . The state court also said trial courts need to `` give jurors specific , understandable instructions that prohibit extrajudicial communications with third parties and the use of technology to obtain facts that have not been presented as evidence . '' `` Trial courts should clearly prohibit jurors ' use of devices such as smartphones and tablet computers to access social media websites or applications to discuss , communicate , or research anything about the trial , '' the court said . CNN 's Joe Sutton contributed to this report .
William Darelle Smith went on trial in 2010 for first-degree murder . A doctor who did the victim 's autopsy testified , then was contacted by a juror . The trial judge did n't order a hearing into that interaction ; high court says he erred . Comment: