legal records

Five years ago I did some research on my father's death in an automobile accident in 1958 and obtained a death certificate and found out that the driver of the other car plead guilty to manslaughter. Suddenly now I am back obsessed with the topic again, and it is very frustrating trying to find more information. What I need is someone in Massachusetts who would be interested in doing a little research for me, but all I can find is endless companies that do background searches of court records for the last 7 years. I can't figure out how to find an individual who does such work and would be able for a reasonable cost to look at the last 40 years.