Just saw this on the UK's Talking Pictures channel (old films & TV) - though I would have seen it back in the 60s when first shown (BBC).
The episode features Inspector Lognon, who appears in a few Maigret books, tall, thin, miserable, always in black, an Inspector in one of the districts for many years, and usually made fun of by other officers. The case features an apparent suicide, but Maigret - who had accidentally heard the phone call come in -- has a sense that all is not what it seems.
He is at pains to keep telling Lognon "it's your case" but keeps one step ahead of his plodding colleague (whose actor doesn't fit the bill of the book's description!). He orders a report on the gun, which shows that a silencer had been used, not at the crime scene, and very odd for a suicide?! Lognon is used as a gentle comedy figure (as is Judge Comeliau in other cases) and a subplot involving a conman also has a few amusing moments.
Warren Mitchell (just before his Alf Garnett starring role) is a bar owner who knew the victim (a diamond dealer) as a nice quiet chap, very polite. But if so polite, why would he call the police to shout insults, just before killing himself? Later they use the bar to observe the victim's flat - and the neighbours.
They discover that the victim''s wife doesn't seem that upset, and that 2 insurance policies will pay out even for a suicide, if enough time has elapsed since taken out -- which it just has! Could the wife have a lover, and if so, where could he be? What is that broomstick doing, when the wife doesn't bother herself with cleaning?!!
Overall, a nice episode, with several supporting actors going on to frequent roles on British TV - and Maigret's suspicious nose turns out to be correct.