Jeffrey Allen Burnham, 46, shot dead his 58-year-old brother Brian Robinette and sister-in-law Kelly Sue Robinette (57) last week in their Ellicott City home, the Howard County police said.
According to the arrest documents, Mr Burnham told another unnamed person that his brother was “killing people with the Covid shot.”
The accused allegedly warned their mother prior to the attack that he wanted to confront his brother because he helped administer vaccines.
Mr Burnham told their mother he believed the government was poisoning people with vaccines and repeatedly said "Brian knows something", the documents stated.
Before killing his kin, the man allegedly stabbed to death his mother's childhood friend Rebecca Reynolds, 83, in Allegany County. She was found dead inside her home with a deep cut across her throat and a pillow over her face.
Mr Burnham allegedly stole Reynolds’ car and drove it for two hours to reach Robinette’s house.
Police investigating Reynolds' murder found her stolen car on Kerger Road and learned that Mr Burnham's brother lived nearby. When the police went to the pharmacist's home to enquire, they found Mr Burnham's brother and his wife lying dead.
Mr Burnham’s mother Evelyn reportedly expressed concerns about her son’s mental health. She had called the Cumberland police two days in a row because of her son’s “mental stability” after he made statements about the FBI “being after” them, the arrest documents filed in Reynolds’ death stated.
She reportedly informed the police that her son lived with her and kept a security system in his bedroom at their home. Ms Burnham called the police again on 30 September concerned over her son’s talk of “Becky’s car,” referring to Ms Reynolds.
The police then sent out an alert to locate the “armed and dangerous” man and offered a reward of up to $10,000 for information leading to the suspect.
The absconding accused was located on 1 October on the side of a road in Davis with a red Corvette that he stole from his brother’s home.
He was arrested by the West Virginia state police the day after he allegedly murdered his brother and sister-in-law.
Mr Burnham has been charged with two counts of first-degree murder and two counts of second-degree murder, along with the use of a handgun in a commission of a crime.