Many conflicting reports, I imagine with all the panic and people trying to swamp the lifeboats though that this could easily be true.
If Officer Lightoller also said "Stand back or I'll shoot you all like dogs" good quote to keep order.
I have never heard of anyone being killed by one of the officers... I think if that were true, it would be well known.
But the rumor of one of two officers committing suicide, is frequently talked about, but I don't know if that is true or not. People can't even decide which one of the two officers it was.
There are reports of officers threatening people with guns, and at least two of them testified to having done so (Officer Lowe testified to firing his gun, not at anyone, but along the side of the ship, to warn people away from rushing the boat as it was lowered; this was shown in the film). However there are no solid reports of Officer Murdoch or any other officer shooting or killing anyone or themselves. None the bodies recovered post-sinking had gunshot wounds (although none of the officers' bodies were found, either).
shareone of the strangest scenes in this movie
"Touchdoooooooooooooooooooooooooooooown Auburn" - Jim Fyffe
Here you can find a list of the people who said that an officer committed suicide or stated that guns were fired:
http://www.williammurdoch.net/mystery02_witnesses_overview.html