Los Angeles Police say Jill Blackstone, drugged her sister Wendy, put her in the garage of the home they shared in North Hollywood, then killed her by setting it on fire, “staging it as an accident”.
Two of their three dogs also died in the blaze.
The Los Angeles County coroner said Wendy Blackstone, 49, died from the effect of the fire on her breathing and of the tranquilliser Xanax.
Although a suicide note was found with the body, a warrant for Jill’s arrest was issued after the 14 March blaze.
Wendy Blackstone was deaf and partially blind and police believe the problems involvedin looking after her sister drove Jill to kill.
A police statement said: “Homicide detectives believe the motive was Jill’s frustration of being forced
to provide Wendy long-term care, as well as the associated financial hardship.”
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Jill Blackstone was arrested in Baltimore, Maryland after checking herself into hospital for a medical condition.
She is expected to be extradited back to Los Angeles.