Complex sentence: District Attorney John Fowler (John Kerr), son of the former DA who retired heartsick over learning he got a wrongful conviction against Elliot, is also unaware his wife Marian (Joan Blackman), is the driver who struck Allison.
Split into simpler sentences: District Attorney John Fowler (John Kerr) is the son of the former DA who retired disillusioned after learning he got a wrongful conviction against Elliot. Fowler is also unaware that his wife, Marian (Joan Blackman), was the driver who struck Allison.