"The stresses of school or being away got to her and she didn't have anyone around," Kajouji's brother Marc tells PEOPLE
Credit: Courtesy Marc Kajouji

Nadia Kajouji was just 18 years old when she jumped to her death from a bridge over Ottawa’s icy Rideau River.

“The stresses of school or being away got to her, and she didn’t have anyone around,” Kajouji’s brother Marc says in this week’s issue of PEOPLE.

Kajouji had suffered the miscarriage of an unwanted pregnancy and a breakup with her boyfriend, but, rather than reaching out to her family, the Carleton University freshman looked to the Internet for a friend.

What she found was far more sinister.

A few weeks before Kajouji’s body was found on the banks of the Rideau in April 2008, the Brampton, Ontario, native posted in an online forum about suicide and got a response from “Cami D,” a self-described 31-year-old female nurse living in Minneapolis.

“I wonder how it will feel to actually die,” Kajouji asked her new friend less than a week before she went missing.

“Nice,” replied Cami D, who went on to enter a suicide pact with Kajouji and urged her to record her final act.

In reality, there was no Cami D.

The screen name was the invention of William Melchert-Dinkel, a nurse and married father of two who used online aliases to urge people to kill themselves.

In fact, Melchert-Dinkel had been busy pushing others to take their own lives since at least 2005.

After his true identity was discovered by Celia Blay – a retired British schoolteacher who had uncovered Melchert-Dinkel’s actions while providing counseling online – the authorities confronted “Cami D” at his home in Faribault, Minnesota.

“He was very unassuming,” retired St. Paul Police Sergeant Bill Haider says of Melchert-Dinkel. “[But] he said five or six people may have committed suicide with his assistance.”

In May 2011, Melchert-Dinkel, now 52, was sentenced to prison for 360 days for “intentionally” pushing someone to commit suicide. But after reviewing the case – which is featured on a June 21 episode of Investigation Discovery’s Deadline: Crime with Tamron Hall – the Minnesota Supreme Court reversed the conviction on First Amendment grounds.

“It was immoral, but that doesn’t mean it was illegal,” Melchert-Dinkel’s lawyer Terry Watkins tells Hall, who also co-hosts the third hour of NBC News’ Today and anchors MSNBC’s NewsNation.

The court drama continues, but Kajouji’s family is ultimately grateful for the media attention given to the case at every legal bump.

“I appreciate the awareness,” says Marc, now a suicide-prevention activist who works with yourlifecounts.org. “Nothing is going to bring my sister back, but if I can help another family, I think that I’ve done all I can.”

Kajouji’s episode of Deadline: Crime with Tamron Hall – which is produced by NBC News’ production arm, Peacock Productions – airs June 21 at 10 p.m. ET on Investigation Discovery.

For more on Melchert-Dinkel’s deception, check out the latest issue of PEOPLE, on newsstands Friday