Police said the 52-year-old Melanie Nash felt she was shorted in her share of the inheritance after her father died in 2004.
She didn't find a will in the casket and her father’s body was left intact.
Nash told police she did not receive anything when her father died and had been thinking of digging up the grave for years to prove that her sister, Susie Nash, hid the will.
Susie Nash has said there was only one will when her father's estate plan was done in 1995 and everyone involved knew about it.
In a written statement to police last June, Melanie Nash wrote that she met up with the others to go to the cemetery.
“All this was done for the right reasons and I know my father would be OK with it,” she said in the statement before ending it with “What we all did was to dig up my father's coffin, Eddie Nash, looking for documents. We did it with respect.”
However, after ransacking her father's remains, Nash found only a packet of cigarettes in his hand, a police affidavit said.
Nash, who faced trial in March, instead agreed to plead guilty to charges of criminal mischief, interference with a cemetery, conspiracy and abuse of a corpse on Monday; her sentencing is scheduled for May.
Mr Nash a one-time dairy farmer started a successful heavy equipment business in 1979, still run by his family. He has since been reburied.
The Colebrook-based company, which employs 30 workers, sells second-hand backhoes, skidders and dozers all over the U.S. and Canada .