UPDATE: June 14, 2017: Police have arrested a 42-year-old Calgary man in connection with the "CanadaCreep" account on voyeurism charges.
A Twitter account that amassed 17,000 followers by posting surreptitiously recorded images of Calgary women's clothed breasts, buttocks and genital areas — including videos filmed up women's skirts while they walked — has been suspended by the social media service.
The "CanadaCreep" account was active for almost a full year and had posted hundreds of photos and videos before Twitter shut it down on Tuesday morning, following numerous complaints.
Alexandra Constantinidis, 22, learned on Monday evening she was among the women whose images were posted to the site.
She said numerous friends alerted her to a nearly minute-long video that appeared to be of her walking in downtown Calgary, filmed from behind and focused on her backside.
When she watched it for herself, she recognized it as being recorded on Friday, as she was going to get lunch.
She then looked through the previous "CanadaCreep" posts, which date back to June 2016, and said she was shocked the account had been so active for so long.
"I was pretty mad that this was happening to me and also to a bunch of younger girls," she said.
"It's a little violating having somebody film you when walking down the street."
Creepy or criminal?
Many of the images were captured on the streets of downtown Calgary, others in and around Prince's Island Park. Some were clearly recorded at a C-Train station or in the city's Plus-15 network of elevated walkways.
Several photographs appear to have been taken during the Calgary Comic and Entertainment Expo in the spring.
Others of a woman in a bathing suit look to have been taken at an indoor pool.
There were also numerous videos in which the camera operator follows women wearing dresses or skirts from behind until the women walk up stairs or there is another opportunity to put the camera low to the ground and point it upward, capturing images of their underwear.
That can qualify as a criminal act in Canada, where surreptitiously recording images up women's skirts where the victims have a "reasonable expectation of privacy" is punishable under the voyeurism section of the Criminal Code.
"The charges may also be more serious if there is intent to distribute the pictures, and depending on who is photographed there also may be a risk of being charged with child pornography," University of Calgary criminologist Michael Adorjan told CBC News.
'Upskirt' victim speaks out
Another Calgary woman, who CBC News has agreed not to identify, said she felt "extremely violated" and unsafe when she learned on Monday night that she was among the "upskirt" victims on the Twitter account.
She said friends alerted her to a series of videos in which the camera operator follows her from behind over a period of several minutes before finally moving in close.
"Eventually he takes the camera and puts it under my skirt from behind. It's crazy," the 25-year-old said.
"You can see my underwear and my butt."
She said the account included so many videos that were apparently recorded over a period of a months, mostly in Calgary's downtown area, it made her worry for her safety and that of her friends and co-workers.
"I feel it's just so degrading. It's just disturbing," she said.
"And then I feel for all the other people that are in the videos."
Police actively investigating
Calgary police said Tuesday they are actively investigating the "CanadaCreep" account for voyeurism.
Staff Sgt. Cory Dayley said some of the videos posted to the account appear to clearly cross the line into criminal territory.
"Anything that's going to be underneath a layer of clothing would be considered an expectation of privacy in our minds," he said.
Police have already saved copies of content that was recorded in Calgary, he added, and they may seek more material saved on Twitter's computer servers as evidence.
Dayley said police were alerted to the existence of the account on Monday evening and were in contact with numerous victims on Tuesday.
It was "alarming" that the account had existed for a year before that happened, Dayley added.
"What's extremely alarming to me, personally, is that this amount of content is out there and it has become this much of a social norm to people to not only see it, but just bypass it in their everyday searches online," he said.
In 2014, Calgary police charged a 27-year-old with voyeurism for an "upskirt" filming incident on a C-Train.
Alberta adopted new legislation in May that makes it easier for people to sue for damages if "intimate images" of them are shared on the internet without their permission.
The man behind the camera?
Constantinidis said she was willing to speak out publicly about her experience because she hopes it will serve as a warning to other women in the city and help stop the perpetrator.
She said her friends who are into cosplay — dressing up like characters from comic books, video games, film and television — were especially alarmed by the surreptitious photos from this year's Comic Expo and have been taking steps to prevent it from happening again.
Several images have been circulating in which the perpetrator appears to capture himself on video — one in which he is pointing the camera upward and seems to catch part of his own face in the frame, and another where he is visible in reflective glass as he records a woman.
CBC News is not publishing the images until their authenticity can be confirmed.
Constantinidis hopes the images will, at the very least, allow organizers of future cosplay-related events to recognize the perpetrator and ban him.
She said she has also been in contact with police about her own experience and hopes security cameras in the area where she was filmed will have captured a clearer image of the person behind the camera.
"I think it's important that we get a clear picture of his face and plaster it everywhere so that everybody knows who he is and is aware to watch out for him and steer clear," Constantinidis said.
"I mean, I'm 22. I've had stuff like this before. But the 15-year-old girls at [the Comic Expo]? That's crushing for them."