Gregorio Concepcion Tyquienco, Contempt of Court, Guam 2025

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Table of Contents

Former Juror gets 30 Days for Contempt in Guam Court

Hagatña, Guam – In a shocking case of juror misconduct, Gregorio Concepcion Tyquienco, a 72-year-old former juror, was sentenced to 30 days in prison followed by one year of supervised release for Contempt of Court, in violation of 18 U.S.C. § 401(3).

The sentencing took place on February 4, 2025 in the District Court of Guam. Tyquienco was also ordered to pay $1,537.04 as restitution (representing the fees and mileage paid to him as a juror during a trial), a $2,000 fine, and a mandatory $25 special assessment fee.

Tyquienco was a juror in the trial of United States vs. Raymond John Martinez and Juanita Marie Quitugua Moser, which took place in the District Court of Guam. Between October 11, 2018, and December 27, 2018, Tyquienco knowingly disobeyed the Court’s instruction not to discuss the case with anyone outside of the jury’s deliberative process.

During the trial, and prior to jury deliberation, Tyquienco discussed what verdict he would render with brothers William Topasna Mantanona and John T. Mantanona, aka “Boom.” Tyquienco knew Boom was working as a member of the defense team. He knew Boom previously but did not disclose the association to the Court. Tyquienco was asked by William and Boom to be the jury foreman and to issue a “Not Guilty” verdict regardless of the evidence.

“Jury tampering is an affront to the Rule of Law,” stated United States Attorney Shawn N. Anderson. “Our citizens and the accused expect fair legal proceedings that result in justice. Jurors and witnesses make great sacrifices to fulfill this important civic duty. This case sends a message that the government will hold accountable those who violate this public trust.”

Tyquienco was investigated by the Federal Bureau of Investigation and prosecuted by Assistant United States Attorney Rosetta L. San Nicolas in the District of Guam. The case highlights the importance of maintaining the integrity and impartiality of jurors and their deliberations in our criminal justice system.