An Old Film title

[Jazzy]

Don't know if anyone can help me but I am trying to find title to a film.  All I have to go on is that a widow marries a man who kills her by using gas from gas piping in her sea side home/cottage.  Her children discover this and I believe they do the same to him.  It could be at least 35 years old and maybe b & w. 

 Thanks. 

[bill107]

Was it Eric Portman in Wanted for murder

[Jazzy]

I do not think so as the film guide suggests he strangled his victims.  In my film he 'gassed' his wife using old gas piping in the house.   Which when discovered her children did the same to him.  I would so like to get a copy of this film but keep drawing blanks.  Many thanks for your answer.