Brian Walshe's smile in front of press cameras, as police escorted him in handcuffs to court, could be used evidence "of a grandiose sense of self-worth," according to a forensic psychiatrist. 

The peculiar moment happened on Jan. 9, a day after Walshe was arrested and charged with misleading a police investigation into his wife Ana Walshe's mysterious disappearance from their Cohasset, Massachusets, home on New Year's Day.

Dr. Ian Lamoureux, a forensic psychiatrist who has conducted over 150 competency evaluations and frequently testifies as an expert witness, told Fox News Digital that there many potential explanations that are "benign."

"Examples include attempting to appear friendly and less 'criminal,' confidence that the evidence against him is weak or even a social compulsion where they have a habit of smiling at others," Lamoureux said. 

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But prosecutors may use it to their advantage, according to Lamoureux, given his reported diagnosis of sociopathy, which was revealed in court documents after the convicted art fraudster allegedly destroyed his father's will and looted the estate. 

"If the state claims that he is a sociopath, they will likely point to this behavior as evidence of a lack of empathy and remorse that is seen in sociopathy," Lamoureux said. "It could also be used as evidence of a grandiose sense of self-worth, as they could argue that he was relishing the publicity his trial is generating."

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A little over a week later – on Jan. 18 – Brian was arraigned on charges of murder and improper disposal of a body in connection with his wife's presumed death. 

During his court appearance, the prosecution detailed 21 alleged Google searches on his son's iPad before and after he allegedly killed his wife, including "Ten ways to … dispose of a dead body if you really need to" and "can you be charged with murder without a body?" 

Lamoureux said that these searches are "powerful" circumstantial evidence, which is what the case is based, on because investigators still haven't found Ana's body. 

"The defendant's searches, if guilty, suggest that he is poorly organized. This is due to their timing," he said. "If the searches are following the murder, they suggest that there was limited planning. He had not thought the crime through from start to finish.

"They also demonstrate that he clearly understands the wrongfulness of murder. These searches clearly demonstrate a deliberate and focused effort to evade criminal detection."

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The searches give prosecutors "a strong argument" for why there is no body, the renowned forensic psychiatrist said. "Simply put, these searches are not something that your average law-abiding citizen does out of boredom or benign curiosity. Contextualize them with the timeline of events, and it appears even more sinister."

There's a split among experts about how strong the state's case against Brian is. 

A Massachusets criminal defense lawyer and a high-profile attorney Iris Eytan, who successfully cleared her client, Barry Morphew, of murder charges, questioned the strength of the evidence presented court. 

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"I’m not saying that he’s innocent, and he’s not responsible, but I’m saying hold off on making any rash judgments," Eytan told Fox News Digital in a previous interview. "When they rush in, and they charge somebody with murder two weeks after the date of someone's disappearance, that's quick without having a body."

A not-guilty plea to all charges has been entered on Brian's behalf, and his lawyer, Tracy Miner, has said in her only statement since the arraignment that she intends "to win" this case in court and not in the media. 

"It is easy to charge a crime, and even easier to say a person committed that crime. It is a much more difficult thing to prove it, which we will see if the prosecution can do," Miner said. 

Despite the purported sociopath diagnosis, Lamoureux doesn't see Miner using a mental health defense because the Google searches "suggest that he understood the wrongfulness of murder at the time of the crime."

"None of his behaviors following the alleged offense suggest he was delusional or untethered from reality in any fashion," Lamoureux said. "No evidence of a history of mental illness has been presented at this point. If he pleads insanity, which is an affirmative offense, he will have to provide an account of the crime, which would have to result in the discovery of the body or trace human remains to hold up to external validation."