Dr. Mark Wangler's two sons, standing behind their father during day eight of his aggravated murder trial.
Wangler is accused of killing their mother, Kathy, by carbon monoxide poisoning.
29 year old Nathan Wangler and 24 year old Aaron Wangler both saying their father was distraught after their mother's 2006 death.
The testimony stands in stark contrast to previous statements by ER doctors, family friends, and Dr. Wangler's in-laws, who said he was emotionless or didn't seem sincere.
Both sons also testified that soot stains in the bedroom where Kathy died had been there for years before their mother's death.
Defense lawyers further trying to chip away at the state's case by bringing in a laboratory manager to review the work of the Wisconsin State Lab of Hygiene, who ran tests for the state.
The Wisconsin Lab experts testified soot in ductwork indicated high levels of particles from combustion engine exhaust. However, defense witness, Laura Stevens, had concerns about their work.
The final witness for the day, Roger Wabeke, an expert in occupational toxicology, provided a new explanation on where the carbon monoxide which caused Kathy's death developed.
He says the hot water heater was the source.
Wabeke pointed out several problems he found concerning the ventilation of the Wangler's hot water heater. He also says the layout of the house and the position of Kathy's bedroom explains why she could have had higher levels of carbon monoxide in her blood than Dr. Wangler.
Wabeke will continue his testimony Friday. Prosecutors have yet to cross examine him. Witnesses for the prosecution had earlier said the hot water heater was not the source of carbon monoxide.
