English murder mystery

I love her but she loves Agatha Christie
And she's so wrapped up in the English Murder Mystery
I was nowhere near the scene of the crime
I was nowhere around at the time
Someone dropped arsenic in Mr Robinson's wine
Getting angry doesn't suit her
Says her English literature tutor

She's a sheep in wolves clothing
It's a bad disguise
I couldn't help noticing with due surprise
That she's dotted her t's and crossed her i's
And she wants to take me away to a hotel in
Bornmouth for the holidays
What's murder and suspense between good friends?

We took a cliched clifftop walk
And I made the mistake of mentioning Peter Falk
She says American TV has killed the murder mystery
'Cause the killer's always caught by 10.23
I had the motive but she gave me the means
A dagger in the drawing room just after tea
She was Miss Scarlet with embarrassment
And envy turned me Reverend Green

I love her but she loves Agatha Christie
She's dead serious about her family history
But she made me promise that I'd never hurt her
She looked so suspicious at the supper I served her
One mans meat is another man's murder
And she wants to put me away in a room without a view for a long holiday

What's prosecution and defence?
What's common law and common sense?
What's a barbed wire electrified fence between friends?