henry rayhons , 78 , was accused of having sex with his wife donna lou rayhons at her nursing home - despite being told her dementia and alzheimers meant she no longer had the capacity to decide for herself .
mr rayhons , who served 18 years as a republican member of the iowa house , had argued that on the night in question he and his wife had been affectionate but had not had sex .
the farmer was emotional as the not guilty verdict was read out at the hancock county courtroom .