Mdthbs

Aaron and his sister Bethany call the police when their live in Grandmother, Candice, failed to get up for breakfast. She was old and ill, and they feared the worst-- especially then they were unable to get into her room! The police break down the door, shattering it in two. Candice is dead, poisoned! The police find

• 8 locks on the door installed by Candice, all of which appeared to be bolted


• a glass of water by the bedside table, half full


• a bottle of heart failure medicine (slow release capsule form)


• 
  The ABC Murders by Agatha Christie, cover torn violently. It now reads "The BC by Agatha hristie"

Forensics find the following:

• Candice died from the poison sometime in the night, around 1 AM.


• No poison in the water.


• No poison in the remaining pills.


• No needle marks.


• No poison on the book, and she wasn't licking it anyway :P


• The poison would've acted quickly, once the lethal dose was absorbed by her system, she would have died in 15 minutes.


• Pathologists do not suspect suicide. In her condition, if she wanted death, all she had to do was stop taking the pills and go to sleep. She'd never wake.

According to interviews:

• Aaron and Bethany confirm that Candice shut herself in at 8 pm. They remained in each other's sight until they turned in at 10.


• Aaron stands to inherit a large fortune. Bethany stands to inherit a small amount by comparison


• Aaron and Candice were getting into arguments, and she began to distrust him. Candice wanted Bethany to pick up her prescriptions, but she was too busy, so Aaron was forced to do it.


• According to her Doctor, Candice knew her life depended on the pills. She did ask that, should life become unbearable, if she would be able to go quietly if she stopped her pills. He said yes.

But! When the will was read... Aaron actually inherited nothing! Candice changed her will last week! Bethany still got her share, but the bulk went to a long estranged nephew living in Ireland! Irish authorities confirm that he has been in Ireland for the past 6 months.

Who murdered Candice, and how?

Hint

There is only one murderer, and Candice figured it out as she was dying. Did she find a way to tell us?

Hint 2

You will not need anything outside the lists to solve the puzzle. I play fair. No one turns out to be a fish or have a high powered sniper poison dispensing rifle :P

Hint 3 -- A big hint

The will change is a clue as to HOW the murder was committed, not who. Agatha Christie is a very intentional reference. The Columbo episode Try and Catch Me also may help you solve this case. If you're familiar with the plot, then you should know what Edmund did. Everything he did.

Edit! I added letters back into the title of the book. Initially I was going to use a different book, so I took out too many letters.

Muderer :

Aaron. The taken out alphabets from the title are A(Aaron) Muders C(Candice).

How

Not completely sure about this, since the story states Aaron was forced to get the medicine, implying he didn't have a plan ready. Anyways I think adding poison in the tablets is really stupid since there was no way for Aaron to know which tablet she'd take first, when and the rest are all OK. It is also possible he didn't care when exactly Candice dies, in which case poisoning one tablet would be the way to go.

Another way could be

He could tamper with the medicine bottle, add a poisonous gas to the bottle somehow so the pills would remain non lethal, but still killing through the bottle leaving no trace of the poison.

While thinking about something else entirely

I think I found another way Aaron could've murdered Candice, provided there's a gap in the door. Aaron could've sealed the door, with plastic, inserted a pipe through the gap and pumped in gas. Bethany would've been in her room and wouldn't find out, there'd be no evidence of the gas, as it would've released slowly throughout the night.

I think it may have been

The Doctor

Reasoning

The letters which Candice tore from the book cover are "A murders C" which, when anagrammed, spell out "Curer's Mad" (she didn't have the letters to spell out Doctor).

How

The doctor had given her an extra pill to take which was laced with poison and told her to take it with a glass of water if she was having trouble sleeping. Being a medical professional, he was able to do it in the correct way so that the poison would take effect only when ingested by Candice. From the last bullet point, Candice seems to put a lot of faith in her doctor so would have no problem accepting his advice.

Sidenote

The normally moral doctor was bribed by a mysterious Irish gentleman standing to come into a significant sum of money.

It was

Aaron

because

what was ripped out from the book was A murders C. Aaron murders Candice?

A possible why:

Aaron thought the he was still receiving the bulk of the will, so he thought that killing her would streamline his wealth. But he didn't know she had changed it so he wouldn't get anything!

A possible how:

Aaron was picking up Candice's pills. It's possible that he slipped one poison pill in there and Candice happened to take it that night...