Murder Mystery edit

[Brownlie]

Deadbolt the doors, the killer is coming.
Not that it matters, soon they'll all be dead.
Breaking the window when thunder's drumming,
no time to dodge a sharp blow to the head.
Quiet but air conditioning's humming, -- Gets a little fragmented here. Imagine making it flow nicely with rhymes and meter and whatnot is a biatch.
one more hour before the killer fled.

Once the dawn broke, the neighbor went inside.
'Dead as a doornail,' describing the scene, -- Would avoid cliches even in dialogue. 
'Quite horrific, she was so young!' she cried.
Not a good witness, there wasn't a thing,
no evidence treachery was implied.
Breaks in this case were thoroughly bleached clean. -- Do you need thoroughly?

Braking hard, roads wet, the Cadillac swerved 
one second too late for a head-on crash.
No trace was left, the killers body burned. -- For a ballad or some sculpted rhyme thing, the terseness seems sort of out of place to me. 
Dead with the money, everything now ash. everything's wouldn't add an extra syllable. 
Not that it matters, the tables had turned, - Tables turned - another cliche. 
quite a discovery was made in the trash.

Quiet so as not to scare him away,
break-ups with lovers are motives enough, -- You're using a to be verb, which is generally a sign of a weak sentence. 
not that an ex-con is prone to foul play,
one only hopes they'd avoid more hand cuffs. -- Isn't handcuffs one word?
'Dead inside, dead to the world,' he would say,
'No way I could have ever done that stuff!'

Knowing full well he hired the assassin,
quite well aware he could go to prison.
Dead-ended life, the price for his passion.
Breaks won't come easy, so unforgiven,
wondering who'll care, he head-strong fastens
knots in the string of his guilt admission. -- Beyond a metrical thing, do you need guilt? admission seems more powerful alone. 

Not that it matters, since everyone died.
Notice the neighbor who first made the call?
One by one, all of the lovers she spied.
Quite content when she saw the bloody sprawl.
Break moral laws, whores are the Devil's bride.
Dead's where they belong, to hell with them all!

No one's suggesting the house was haunted,
quiet naughty influence, undaunted.
Deadly though, to break anyone taunted.

I think this should be smoothed out if you want to edit.