It's been nearly a week since Tomas Herrera went missing from his Primera home. His daughter-in-law, Sonia Herrera, knows time is running out. "Whether he's alive or he's deceased... We just want closure... That's all we want," she said. The 78-year-old suffers from a number of medical complications, including early signs of dementia. His family members often hit the streets to try and find him. Sonia searched one of Tomas' treasured spots on Tuesday. It's at the Combes Harlingen Memorial Cemetery. Every Sunday, Tomas would visit his late wife Aurora's grave site. Her birthday would have been this Wednesday. Sonia said they're running out of areas to search. Canals, ditches, irrigation places... fields, stores, hospitals, you name it," she listed. Making matters worse, a state Silver Alert has expired. Resources to locate the missing elderly man are limited at the police department. Like an Amber or Blue Alert, Silver alerts are only typically activated by the state for a period of 24 hours. That's because time is of the essence when it comes to getting the public's help. Sonia felt like more needed to be done. "I don't understand why the Silver Alert was taken off... this is a human being," she said. Tomas recently cashed his disability and social security checks. Sonia is afraid he could be robbed or worse left to die. She can't help but feel responsible that he has yet to be found. "To tell you the truth... I felt like a failure...I don't like failure... I really don't," Herrera said. Tomas Herrera was last seen driving a 1991 light blue Chevy pickup. If you have any information on his whereabouts, please contact Primera police at (956) 536-1062.