The Behaviour Effect

Whilst reading a light-hearted book on philosophy by Peter Cave I came across this rather interesting example of actions, intentions and their consequences.

Three singers, June, Gill and Jon, are treking across the desert.  June and Gill dislike Jon but have not voiced their dislike to each other.  They each and separately decide to kill him.

June sneaks out of her tent at night and puts poison into Jon’s water bottle.  Gill, not realising what June has done, sneaks out of her tent and cracks the bottom of Jon’s water bottle so that the water leaks out.  They both pack up the following morning and leave before Jon awakens.

Jon wakes up in the morning to find his water bottle empty and dies of dehydration.

Can either June or Gill be held accountable for Jon’s murder?  Is it actions or consequences that matter?