A Quick Murder

What are some ways to murder someone in a relatively short amount of time, preferably something not terribly gruesome (so that you could still identify the body afterward). Normally, I'd just use a gun, but for this case, it cannot be one because I don't want a bullet wound.

You could sneak up on him (or her) and slit his throat before he realizes anyone is there (or make him drunk/stoned/etc. so he can't fight back, if that fits your character).It'd be fairly gruesome, but the body could easily be identified. You could also have the murderer slip something in his drink (either poison or drugs to keep him from fighting back).

Quick and gruesome are both pretty subjective. Stabbing someone in the chest and penetrating their lung would kill them fairly quick, as their lung fills with blood and they "drown", breaking someone's neck is fairly quick though the person doing the breaking needs to be pretty strong...not the hulk mind you, but a 90lb woman is unlikely to get the job done...so just depends. Could you share more about your killer and how quick it needs to be?

Strangulation with a garrote is another idea. Depending on the type of garrote used, it would be quick and relatively bloodless, unless the garrote is a wire or something that cuts the neck.

How about a nice pillow to the face?

If u want body most intact, then a strong poison is ur best bet - will just have some bodily fluids coming out of pores. But snapping the neck is the quickest way. A good hit to the right spot, like the temples,is also an option

Drowning. You could slip them some drugs or get them drunk so it would be easier to gain the upperhand; or else just use old-fashioned surprise. You could drown in three inches of water, so I've read.

Slip a knfe in at the base of the skull. Quick, silent and professional with minimal blood.
In one of the books I've read a shaman hides the fangs and venom sack of an extremely poisonous snake in his hand and slaps anoter man on the head, leaving two tiny puncture wounds hidden by the victim's hair and enough poison to kill eight grown men in his blood. At least in the book, that was pretty quick, but painful. You'd want to gag your victim, mehinks.