SALEM – A Salem Superior Court judge will rule Dec. 5 on whether charges can be dropped against Ernesto Gonzalez, a Lynn man found mentally incompetent to stand trial for allegedly kidnapping his 5-year-old son in 2008.It is the third continuance – and second in two days – on the matter, as attorneys dispute whether Gonzalez should receive credit for time served behind bars now that he is incompetent for trial.Gonzalez has been held since he was charged with parental kidnapping and misleading investigators in the disappearance of his 5-year-old son Giovanni in August 2008. Gonzalez was the last person seen with the child, and Gonzalez later told a reporter that he killed and dismembered the boy. But Giovanni has never been found, and the boy’s mother believes he is still alive.State law allows defendants who have been declared incompetent to stand trial to file for dismissal of charges if the defendant has served at least half the maximum sentence he or she would have received if convicted.Defense Attorney Russell Sobelman argued in a hearing last week that Gonzalez had reached that point, having been held for five years – half of the 10-year sentence for a conviction of misleading investigators.But Essex Assistant District Attorney Jean Curran suggested the time considered in regards to the state law should be calculated from the time the defendant was found incompetent, not the time the defendant was initially incarcerated.Judge John Lu said he would consider the motion and issue a ruling Wednesday.But when calling the case Wednesday, Lu asked for an official calculation from the Department of Corrections (DOC) of how much time Gonzalez had been incarcerated and thus when he would be eligible to apply for dismissal. When that number wasn’t available by the end of the day, Lu continued the matter to Thursday.On Thursday, the Department of Corrections gave a “preliminary number” but one that had to be “reviewed up the chain of command,” Lu said.Lu didn’t cite any specific number, but mentioned a 2017 date. Sobelman said this was the DOC’s calculation of time Gonzalez would be eligible for dismissal, which suggests the DOC was not using the 2008 arrest date.But Lu specified repeatedly Thursday that it was a preliminary figure. He ordered the hearing continued to Dec. 5 and that the DOC provide an official calculation and a recent report of Gonzalez’s mental health. But even if the kidnapping charges are dropped, Gonzalez faces an assault charge in another case and has been civilly committed to a state psychiatric facility.