The two people accused of planning to open fire at a Halifax mall will be in court Tuesday.

James Gamble and Randy Shepherd grew up together in Timberlea, N.S. Neighbours confirm that they both graduated from Sir John A. MacDonald High School. They had jobs and no criminal records.

What wasn’t well known was what they did online.

Both had Tumblr pages with violent images of the Columbine murderers and Neo-Nazi symbols.

Psychology professor Steve Smith says people look for acceptance by seeking out others who share similar beliefs. They often find each other online.

“What happens is you have a certain set of interests,” he says. “And when you interact with each other, you become more extreme.”

Police allege Gamble, along with Shepherd and Lindsay Souvannarath were plotting to kill as many people as possible at the Halifax Shopping Centre on Valentine’s Day.

Police intervened after someone called Crime Stoppers.

Gamble shot himself at his parents’ home. Shepherd and Souvannarath were arrested by police at the airport.

Authorities say Souvannarath flew to Nova Scotia from Illinois.

A note posted at her family home just west of Chicago reads, ‘We are very sorry, but we are not prepared to make a statement at this time.’

Souvannarath graduated from Coe College in Iowa in 2014 with a Bachelor of Arts degree, double majoring in English and creative writing.

Police say she met Gamble and Shepherd online.

According to Smith, online groups that talk about violence are not uncommon. But he says there are very few people who are actually willing to commit a violent act.

“We have lots of people who have extreme views and express extreme interest,” says Smith. “But they aren’t harmful to anybody or even themselves, but when there is risk that’s when there is a problem.”

Smith adds that it’s possible that even those close to people who show a dark side online may not be aware.

“The natural tendency is to blame and say someone must have known this was happening,” notes Smith. “Not necessarily. It’s very easy for people to have an online presence that other people don’t know about.”

Souvannarath and Shepherd will appear in court Tuesday. They are both charged with conspiring to commit murder.

With files from CTV Atlantic's Kelland Sundahl