MUNSTER, Ind. (CBS/WBBM) — Police in Northwest Indiana say the more time that goes by, the more likely it is that foul play may have been involved in the disappearance of a 70-year-old eye doctor.

Dr. Promila Mehta-Paul, 70, was last seen on March 21. Her 2001 gold Toyota RAV 4 also remains missing.

As WBBM Newsradio 780’s Steve Miller reports, one of the doctor’s sons spent time in a California state prison.

LISTEN: Newsradio 780’s Steve Miller reports

The charge was burglary, and the conviction resulted in a two-year sentence. Mehta-Paul’s son served less than a year and was paroled, and the parole ended last July.

Part of that case had involved a charge of assault with a caustic chemical, but it was dropped.

The same son admitted to a misdemeanor charge of battery in Indiana eight years ago.

Four days before his mother disappeared, he pleaded guilty to misdemeanor DUI.

When asked to comment on the investigation, a Munster police spokesman said, “We don’t have any people of interest right now that we’re naming.”

Mehta-Paul was last seen on March 21 by workers at her eye clinic in Highland, Ind.

Last week, police released a new image showing Mehta-Paul making a deposit at a First Financial Bank branch in Highland, also on March 21. Her missing vehicle is in the background.

Police say they continue to interview the doctor’s family and co-workers.