Nadire Atas, a Canadian who wrote thousands of online posts defaming her supposed enemies, was arrested by Toronto police on Tuesday. She has been charged with crimes such as harassment and defamation, a Toronto police spokeswoman said.

Ms. Atas, 60, has waged an online war against dozens of people in the past few years, falsely accusing them of being scammers, thieves, sexual deviants, and pedophiles. Her goals included a family she employed 30 years ago; your mortgage lender; Lawyers she fought in court and those she represented; and the family members and colleagues of these people.

The arrest and prosecution followed an article published January 30 in the New York Times detailing her campaign against harassment and defamation. It illustrated the destruction one person can wreak thanks to the hand-off stance of big tech companies like Google.

Ms. Atas has been charged with 10 charges of harassment, defamatory slander and disseminating false information to raise the alarm, said Caroline de Kloet, the police spokeswoman. “This was a lengthy, complex investigation that involved numerous victims,” ​​she said.

Last month, a Toronto judge ordered Ms. Atas to stop her online attacks on 45 people whom she had sued for defamation. However, posts about the plaintiffs and their families continued to be published on sites such as BadGirlReports and Cheaters.News.

Ms. Atas, who told The Times that she had a history of mental health problems, did not respond to requests for comment on her arrest.

The targets of Ms. Atas’s attacks – including Guy Babcock, whose family she employed in his Canadian real estate office – tried for years to get law enforcement agencies to prosecute her and filed police reports in the U.S., U.K. and Canada where her victims were living . The criminal complaints filed this week are the first that Ms. Atas has faced in relation to her online posts.

Police recently took an interest in the case, said Christina Wallis, a lawyer who has been involved in litigation with Ms. Atas since 2008 and was the target of her online attacks.

The day after The Times published their article quoting Ms. Wallis extensively, a website called GossipBlaze.com sent her an email believing that Ms. Atas “had our submission form with ten, if not hundreds spamming posts ”.

“Almost all of them have the same IP address and we thought it might be helpful to give you that information,” read the email, which relates to an Internet Protocol address, a unique identifier that was used by a computer or a computer network.

Ms. Wallis shared the email and IP addresses of a group of victims who had previously contacted the police. One of them, Luc Groleau, determined that the IP address most likely came from a computer in a hotel in east Toronto. Mr. Groleau shared the information with a lawyer who said he had alerted the police to Ms. Atas’s whereabouts.