Canadian Al Amin Dhalla, 42, acquired a number of weapons, a modified van with a cage and other equipment after he was jilted by a woman he met online.
Dhalla moved into the home of Dr Alison Hewitt, 35, in Brighton, East Sussex, months after they met through an online dating agency for professionals.
But relations soured after Hewitt’s family voiced concern over his “unseemly haste” to marry her and over lies they uncovered about his past. The couple split after a year, triggering a terrifying four-month campaign in which Dhalla tried to burn down Hewitt’s mother’s home and hired a private investigator to spy on her.
At Lewes Crown Court, ex-City auditor Dhalla was found guilty of seven counts, including arson being reckless as to whether life is endangered, attempted arson, harassment of Dr Hewitt and her mother, theft and damaging property.
He was found not guilty of two counts of the more serious charge of putting a person in fear of violence by harassment.
Dhalla was also convicted of perverting the course of justice and having an offensive weapon.
Dr Hewitt said outside Lewes Crown Court: “I feel very relieved that it is all over now. I’m looking forward to getting back to my normal life.”
Dhalla stalked Dr Hewitt by posing as a doctor at the hospital where she was due to start work and asked to see the trainee doctors’ rota. He bought two mini-crossbows and a 1.77 air pistol with ammunition for both and a van specially adapted to include a cage in the rear.
At the height of the harassment, police airlifted Dr Hewitt’s mother, Pamela Hewitt, and stepfather, David Gray, from their holiday home on Lundy Island, Devon, amid fears for their safety.
A senior detective believes they prevented Dhalla — described by Miss Hewitt’s family as a “narcissistic psychopath” — from committing three murders.
The trial heard Dhalla came to Britain in 2009. A year later he met Dr Hewitt through an internet dating agency.
Prosecutor Richard Barton said Dhalla moved himself into her home in Church Place, Brighton, but cracks soon appeared in Dhalla’s claims about his background. Gray’s role in the defence industry required him to tell his employers about any changes in his family’s circumstances. Through his own inquiries and those of his employer, it emerged that Dhalla had lied about his past.
He falsely claimed that he was 35, an orphan and had lived in Britain for several years. He also did not mention a conviction in Canada for assaulting his uncle with a weapon.
His lies led to him being suspended from his job in Dec 2010 and in the same month Dr Hewitt decided to end their relationship.
The court heard that Dhalla’s behaviour turned increasingly erratic and sparked a manhunt involving five police forces. He refused to move out of her home, forcing Dr Hewitt’s relatives to evict him.
On April 1, Gray and Pamela Hewitt went on holiday to Lundy Island. The next day, after buying a .22 air rifle, a 1.77 air pistol and two mini crossbows, Dhalla was arrested near Chippenham, Wiltshire, while firing his weapons in target practice.
Inside his van were masking tape, tools, fuel cans and details of locations, said to include Mrs Hewitt’s and Gray’s holiday spot, their home addresses and hospitals where Dr Hewitt worked.
Judge Charles Kemp adjourned sentencing to April 16 and requested psychiatric and probation service reports.