HALIFAX -- They started sending online messages to each other on Dec. 21, 2014, an innocuous online chat about coffee and creative writing.

But the conversation between Lindsay Souvannarath and James Gamble quickly devolved into a shared admiration for the Columbine killers, mass shootings and a murderous conspiracy to go on a Valentine's Day shooting rampage at a Halifax mall in 2015.

The Facebook messages, shared over seven weeks, were entered into evidence Monday at the sentencing hearing for Souvannarath, who pleaded guilty to conspiracy to commit murder last April.

The Crown is recommending a sentence of 20 years to life in prison, while the defence says the sentence should be 12 to 14 years, with credit for time served.

Nova Scotia Supreme Court Justice Peter Rosinski reserved his decision until Friday, calling it a "very unusual and difficult case."

When the judge asked Souvannarath if she would like to address the court prior to her sentencing, the 26-year-old from the Chicago suburb of Geneva, Illinois, said only "I decline."

Crown attorney Shauna MacDonald said Souvannarath hasn't renounced her views, and remains an ongoing danger to the public.

"We have no evidence before us that her views have changed in any way," she said outside the courtroom, adding that the plot came very close to being carried out.

"The sense of safety and security in the community has been changed because people now know that this can happen in Halifax, and it almost did."

Souvannarath's co-conspirator, 19-year-old James Gamble, killed himself as police tried to arrest him at his Halifax-area home a day before the planned attack. Randall Steven Shepherd -- a Halifax man described in court as the "cheerleader" of the shooting plot -- was sentenced to a decade in prison in 2016.

The 1,205 pages of messages between Souvannarath and Gamble were obtained by the Kane County Court in Illinois, which ordered Facebook to produce the chat logs.

The conversation exposes gruesome details about the foiled plot to kill as many people as possible in the food court of the Halifax Shopping Centre, and shaped much of an agreed statement of facts presented to court Monday.

"They both expressed enthusiasm for the pain/death they were going to cause," the document said. "They both deeply desired to achieve infamy and notoriety through the mass killing of others."

It added: "They revelled in thinking about the pain and anguish their families would feel at their horrendous act. They hoped their massacre would inspire others to do the same."

Both Souvannarath and Gamble were unemployed and lived with their parents.

Gamble had previously asked Shepherd -- one of his few friends -- to join the plot. Shepherd resisted, but helped Gamble prepare, including recording videos of where the attack was to occur.

During their lengthy online conversation, Souvannarath and Gamble discovered they both admired the 1999 Columbine High School massacre in Colorado in which teenagers Eric Harris and Dylan Klebold killed 13 people and themselves.

Gamble had been considering a mass killing and began to follow Souvannarath's blog, which was filled with racist and violent material and subtitled "School Shooter Chic."

The two soon began communicating via Facebook, exchanging sexual messages and expressing "a shared connection."

They spent about seven weeks plotting a plan they called "Der Untergang" -- The Downfall.

"Souvannarath and Gamble repeatedly stated that they were adopting the personas of Eric Harris and Dylan Klebold, respectively. They would often refer to each other by the nicknames of Harris (Reb) and Klebold (VoDKa)," the agreed statement said.

"They would quote passages to each other from the publicly accessible journals of Harris and Klebold."

They chose the mall as their target to cause "mass panic."

The pair planned to wear masks and use a shotgun and hunting rifle owned by Gamble's father, and begin the massacre with Molotov cocktails, it said. After the massacre, they planned to kill each other.

"They believed their destiny was to commit this massacre," according to the agreed statement. "She commented that committing a mass killing would punish the popular and hurt those who never understood her."

Gamble had planned to kill his parents before the massacre, and then he and Souvannarath, who were both virgins, would consummate their relationship.

They had planned Tumblr posts for the day after the massacre, to boast about the shooting.

The plot was foiled through an anonymous, detailed tip to Crime Stoppers, including Gamble's name and the air travel plans of "an Asian female, known as Lindsay."

Souvannarath has been in custody since her arrest after arriving at the Halifax airport on a one-way ticket from Chicago, according to the agreed statement.

The agreed statement said Souvannarath saw herself as racially and intellectually superior and "expressed her belief that she is a sex goddess with superior intellect who is entitled to cull the inferior," and that "racial and ethnic realities must be righted through violence."

It includes a transcript of her conversation with an undercover officer posing as a fellow prisoner, with her laughing as she detailed her plot: "It was going to be a Valentine's Day massacre."

The agreed statement also has a note found in her cell, framing the plans for a murder plot with romantic urgency: "I was to be his Eric Harris and He (sic) would be my Dylan Klebold ... Eventually, I realized that we really were Eric and Dylan, their minds having taken refuge in our bodies some time after their demise in 1997."

Crown lawyer MacDonald said the plot was "carefully considered" with "cold calculation and enthusiastic resolve" for maximum carnage, public shock and notoriety.

"The enormity of this crime cannot be overstated," she told the court. "The potential loss of life was overwhelming."

However, Luke Craggs, the defence attorney for Souvannarath, argued that while many aspects of the conspiracy were planned out, there was virtually no thought afforded to "actual concrete logistics."

"She showed up at the airport with a half-cooked story, a one-way ticket and $33," he said in court, later telling reporters that "One of the things that determines the length of a sentence is how real the risk actually was."

When asked if she was remorseful, Craggs said it was "difficult to say. She's not a particularly chatty person."

But he added that "no one sort of does this, gets caught and then has to face punishment without some degree of introspection."