Miss Smith wrote to Miss Nelson to say she could not change reality.
According to the Orange County Register, Miss Nelson allegedly convinced Mr Zamora to help in the killings by promising to provide him with gay lovers.
The pair then travelled more than 4000km across the country to California where Mr Zamora stabbed Miss Smith while Miss Nelson allegedly killed Miss Vo.
The bodies were found with their wounds painted white in an apparent attempt to hide the injuries.
Cash and jewellery were allegedly stolen from the bodies.
Mr Zamora has pleaded guilty to murder and is facing a minimum of 50 years in jail.
The hitman has been the star witness for the prosecutions’ case against Miss Nelson who has been charged with two murders and is facing the death penalty if convicted.