Robert Schenker was found dead at his Peterborough home
A builder whose work caused the death of a man from carbon monoxide poisoning has been found guilty of manslaughter.
Mechanic Robert Schenker, 31, was found dead at his home in Peterborough, Cambridgeshire, in March 2006.
Three days earlier builder David Johnson had started reconstructing a chimney, Norwich Crown Court heard.
Johnson, 56, of Peterborough, had denied manslaughter and exposing Mr Schenker to risk. He has not yet been sentenced by the court.
The court heard Mr Schenker needed some work carried out on his chimney and called in Johnson.
After it was completed, Mr Schenker telephoned the builder and asked if he could turn his boiler back on and was told he could, the court heard.
The prosecution used a camera to photograph debris in the chimney
Johnson had allowed mortar to drop into the chimney, which was connected to the flue pipe on Mr Schenker's kitchen boiler, prosecutor Deanna Herr said.
The mortar solidified and blocked the chimney, preventing carbon monoxide from escaping into the atmosphere, she said.
The poisonous gas leaked into Mr Schenker's home and killed him, jurors were told.