59-year-old David Cook of Dedham and his 31-year-old son Daniel are being tried together. David Cook is the former Otis town clerk.
A third man charged in the crimes took the stand Thursday: 20-yea-old Christopher Lapointe of Orrington has already pled guilty in the case.
Lapointe testified that both of the Cooks helped him with the break-ins.
Police say thousands of dollars worth of items were taken from 30 different camps.