Is there a way to pursue someone for taking advantage of the elderly?

They also were taking money and not paying back. My elderly father gave a large loan to a local business man with promise of payment in full. No paperwork was done. Does my dad have any legal recourse since the business man has not paid him back as promised? My dad does have proof of the few small payments made back on loan. My dad could not afford to give someone this size of a loan, but was guilted into it.