A state insurance corporation receives a claim under an insurance policy on the life of Muppet who was recently found shot dead. The police suspected that she was murdered by Tim, who was the sole beneficiary under Muppet's will. Tim has since committed suicide. The terms of the insurance policy state that the Corporation is not liable to pay any of the proceeds of the policy in the event of the insured having been killed by the beneficiary. The Corporation has now decided not to accept the claim and Maria, Tim's widow and sole beneficiary under his will, brings an action against the Corporation for the insurance monies. Upon whom is the burden of proof and what is the required standard of proof?

With 2000 words, discuss and support your answers with some cases using UK legislation .