NORWICH – Police say a grandfather knew his family members were going to try to burn down their Coventry home last August.

The Chenango County Sheriff’s Office arrested the grandfather, 70-year-old Joseph S. Dietzman, his daughter, 36-year-old homeowner Kimberly Koster and her daughter, 17-year-old Chelsie M. Koster, following investigation into a Coventry blaze on Aug. 13.

Dietzman appeared in Chenango County Court Friday during an arson evidence hearing, at which police contended he admitted to having knowledge of the crime before the home was set ablaze.

All three co-defendants were indicted Oct. 20 for third degree arson, a class C felony, and fourth degree conspiracy, a misdemeanor, after they allegedly collaborated in burning down the Kosters’ Coventry home.

“The defendant did intentionally damage her dwelling by pouring gasoline inside her residence which was later set on fire by a co-defendant, causing complete loss of the residence,” stated Kimberly Koster’s indictment.

The indictment identified that codefendant as her daughter, Chelsie. She participated in the incident “by starting a fire when she intentionally lit a match and placed it on a pile of clothes inside the residence,” according to the indictment.

The two were arrested after evidence testing identified gasoline as the substance used to start the fire, police said.

Several area fire departments responded to the fire at 10:20 p.m. Aug. 13, at 1636 State Highway 235, after a neighbor called 911.

Firemen arrived to find the home unoccupied and engulfed in flames. Within a few hours, investigators inspecting the debris found evidence of foul play and contacted the Sheriff’s Office.

Lt. Richard Cobb said police spoke with home’s owner, Kimberly Koster, and received conflicting information about the incident.

Dietzman was arrested in early November after the Kosters were charged, and for the first time Friday, police portrayed his role in the crime during an evidence hearing.