A Burnaby B.C. man accused of criminally harassing his ex-wife promised to "slowly and incrementally destroy" her using a website and emails, a jury heard Monday in B.C. Supreme Court.

Patrick Fox, 43, is accused of systematically attacking his former wife, Desiree Capuano, 36, after she tipped off the Federal Bureau of Investigation (FBI), during a contentious custody battle, that he was living illegally in California in 2012 

This week, Fox, who is representing himself during the criminal proceedings, appeared calm and polite in court, wearing a red prison-issued sweatsuit and carrying a box of legal documents.

Capuano sat behind a screen to prevent any visual contact between her and her former husband, but the judge instructed the jury not to interpret this as a sign of innocence or guilt in the case.

Capuano, who once shared custody with Fox, told court she became wary when her former husband changed his name, fearing he would disappear with her son, as she alleges he did between 2001 and 2011.

"I was scared if he took my son to Canada, I would not see him again," she said, her voice often wavering.

Patrick Fox says he will maintain website as long as ex-wife is alive

The trial of a Vancouver man who the Crown contends tried to 'ruin' his ex-wife's life with emails and a website began Monday in B.C. Supreme Court. (CBC)

The Crown confirmed that Fox had changed his name from Richard Riess to Patrick Fox in 2014 and moved to Canada where he was able to obtain a Possession and Acquisition License (PAL) and buy guns.

Police later discovered that Fox had shipped several guns hidden in a computer to the U.S. 

It's unclear why.

The jury listened and followed along with a thick compilation of emails —​ agreed to by both sides as fact — as Crown counsel Mark Myhre read parts into the record yesterday, and Capuano responded to questions about them.

In one email, Fox allegedly outlines his long-term plan to "ruin" Capuano's life and hurt her "emotionally," according to Myhre.

"I told you I will destroy you slowly and incrementally (and legally). I will do so simply by using your own actions and words against you. Don't think for one second that anything will ever be more important to me than destroying you. Every moment of my life is focused on one single goal," Fox allegedly wrote.

Court also heard how Fox allegedly bragged he copied 600 to 1,200 people, including co-workers, on emails that insulted Capuano and detailed her personal life.

She said most of the more than 400 emails referred to her as "white trash" or offered a similar insult.

Fox also posted images of Capuano semi-clothed after a shower and of the bedroom itself. Another email informed her workplace that she was a medical marijuana user.

"Mortified," said Capuano in court yesterday, when asked how she felt about personal information that Fox shared with co-workers and strangers alike.

Capuano sought help from police, workplace security and eventually cut off all communication with Fox, but the online onslaught continued.

Eventually, the Information Technology (IT) worker lost her job in 2015 and said she was told by a co-worker that "security risks" because of the online attacks were part of the reason.

Fox defended his actions to Capuano in emails saying that "telling the truth is not harassment."

In one message, court heard Fox bragged to Capuano about how he'd waived his rights to his son in a California court so that he could dedicate his time to attacking her and copied their son on that email.

"Why did that hurt you?" asked the Crown.

"[Because] it hurt my son," said Capuano.

The Fox trial is expected to continue for up to three weeks.

Justice Heather Holmes cautioned the jury not to look at the website that is at the heart of the case or at media reports.

The defence has not yet been heard.

With files from Natalie Clancy