Mardyla, originally from Krakow in Poland, has lived in Stockholm for more than twelve years.

On April 20, she was getting ready to fly home to Poland for a visit.

“She checked the flight numbers with her flatmate, and then left the house around 6pm,” her sister Barbara Mardyla told The Local.

Agnieszka Mardyla continued to text with her flatmate for another couple of hours on Friday evening.

“Since then, no one has heard from her,” her sister said.

Both Polish and Swedish police have been informed of her disappearance, but remain stumped as to what lies behind it.

Friends and family are also unsure what may have caused Mardyla to disappear.

“We’ve been trying to come up with reasons for it, but haven’t been able to. If I only knew why, this would feel easier,” Barbara Mardyla said.

“I’m so worried about her. I really hope she’s okay.”

Any readers with information relevant to the case are advised to call the Swedish police at 114 14.