Authorities are searching Friday for a missing 33-year-old Marine who served multiple combat tours in Iraq and Afghanistan.

The Hamilton County Sheriff’s Office has issued a “critical missing person” alert for Anthony “Tony” Pastura, who was last seen in the Cincinnati area on Monday.

"Anthony suffers from Post Traumatic Stress Disorder (PTSD) and has made previous suicidal threats,” police said in a statement.

Pastura -- a Marine from one of the heaviest-hit units of the Iraq War -- is possibly driving a dark blue, 2006 Jeep Grand Cherokee with an Ohio Licence Plate 169YIE, authorities said.

A family friend of Pastura's told Fox affiliate WXIX that his cellphone pinged somewhere along the Arizona-New Mexico border on Tuesday.

Police did not confirm the cellphone ping. A spokesman from the Hamilton County Sherriff's Office told FoxNews.com Friday morning that there have been no known sightings of Pastura.

Pastura served as a mortarman with Columbus-based Lima Company, 3rd Battalion, 25th Marines, according to MilitaryTimes.com. Pastura left the Reserve as a sergeant in December 2012.

Pastura is reportedly the recipient of the Navy and Marine Corps Achievement Medal, Combat Action Ribbon and two Selected Marine Corps Reserve Medals. 

"He's the most energetic, loving guy," family friend Annie Ey said at a prayer service for Pastura on Wednesday, WXIX reported. 

"He's a great father," added Ey, who said she last saw Pastura about a week ago.

"He's had his ups and downs but he seemed OK," she said. "He seemed like he was on the upswing of things."

Anyone with information on Pastura's whereabouts is urged to contact detectives at 513-851-6000 or CrimeStoppers at 513-352-3040.

FoxNews.com's Cristina Corbin contributed to this report. 

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