CROWN POINT, Ind. (CBS) — A judge has refused a request by the sons of missing Northwest Indiana doctor Promila Mehta-Paul to name a legal guardian for her estate.

Mehta-Paul’s sons, one of whom has been named a person of interest in her disappearance, were surprised by the decision Thursday by Lake County, Ind., Judge George Paras.

The sons had asked Paras to appoint John Argus and his Munster-based American Management Systems International as legal guardian of Mehta-Paul’s estate.

Mehta-Paul , of Munster, was last seen on March 21 and did not show up for work at her eye clinic in Highland the next day, despite having several appointments scheduled. She had left her office the day before and deposited money at a First Bank branch in Highland, but disappeared soon afterward.

Police now believe Mehta-Paul is dead, and they say one of her sons, Paresh Paul, 38, is responsible. But he has not been arrested or charged.

Munster Detective Mike Janiga testified he has logged more than 100 hours on her case, and others from his department have spent many hours working on it, along with officers from the Highland Police Department, FBI and the U.S. Border Patrol. Janiga confirmed Mehta-Paul is missing and her whereabouts are unknown.

“All the leads have been followed to no avail,” he said.

Munster police have not specified exactly how or why Paresh Paul was involved in his mother’s disappearance.

Police did say Paresh Paul was with his mother on the night of her disappearance and shortly thereafter left the area. In addition, Paresh Paul has been questioned by officers several times and has made several inconsistent statements.

Argus, whose company specializes in valuing, managing and liquidating assets in bankruptcy cases, testified about his qualifications as a prospective guardian.

Paras nearly named someone else Mehta-Paul’s guardian, but attorneys representing the Paul sons objected and sought another hearing.

In July, Paresh Paul hired St. John attorney Laura Rybicki and sought appointment as his mother’s guardian, which would effectively allow him control over her estate. That estate includes business and personal property and financial assets. To prevent that, his younger brothers hired American Management Systems International to seek court appointment as her legal guardian.

On Wednesday, Rybicki confirmed all three brothers consented to hire American Management as guardian, avoiding a costly fraternal legal battle. But none of the Paul sons showed for the hearing and Paras questioned whether American Management had any legal standing.

Rybicki and Merrillville lawyer Geoffrey Giorgi, who represents American Management, said their clients chose Argus’ company. But Paras remained unconvinced, noting that this was no ordinary guardianship hearing and that a missing person was involved. Because of “the uniqueness of the situation,” Paras denied the petition to appoint American Management. However, Rybicki and Giorgi persuaded him not to appoint another guardian until they could discuss it with their clients.

Paras set the next Mehta-Paul guardianship hearing for 8:30 a.m. Sept. 27 and said he hoped all interested parties would attend.

Meanwhile, Munster police ask that anyone with information about Dr. Mehta-Paul’s disappearance, or the travels of her son in late March, contact them at (219) 836-6600. Anonymous information can be left on the department tip line at (219) 836-1010.

The Northwest Indiana Post-Tribune contributed to this report, via the Sun-Times Media Wire.