A probe into an incident which occurred on a Stena Line ferry has taken a chilling flip after police steered a stunning idea.

The tragedy, beforehand believed to be centred on a heroic mom diving into raging Swedish waters to avoid wasting her son, is now being investigated as a murder-suicide.

Swedish police trying into the circumstances round that incident that occurred on Friday have now modified their idea about what may have occurred.

They consider that the mom could have intentionally jumped overboard along with her son.

The new resolution to deal with the incident as a possible murder-suicide has despatched shockwaves via fellow passengers because the thriller deepens.

The mom and son who went overboard have thus far solely been recognized by their first names, Paulina, 36, and her son Lech.

The pair, each from Grudziadzt, Poland, had been on the Stena Spirit ferry because it travelled from Gydnia, Poland, to the Swedish port of Karlskrona when the tragedy occurred.

After they fell in, an infinite search and rescue operation was launched with NATO aircraft known as in to help.

The mom and son had been discovered and airlifted to a hospital, however they couldn’t be saved and each died.

In the speedy aftermath of the incident, it had been reported that the mom had dived into the ocean to avoid wasting her son.

However, this modified when eyewitnesses who noticed them simply earlier than the tragedy occurred described Paulina as “tired” and “depressed”.

Beata, a fellow passenger, informed Fakt: “I remember thinking it was unusual to have such a big baby in a stroller, but the boy may have been disabled in some way.

“She looked tired, depressed. Her body language was so... I was walking past her. Now I wish I had asked her any questions, made contact, anything.”

Beata added: “I didn't get the immediate impression that she needed help, but it would be better if I stayed by her side. But it was cold and I hid below deck.”

The investigation has been led by Swedish police with Polish colleagues helping as they attempt to piece collectively what occurred.

According to the Swedish Police’s Thomas Johansson, there have been a number of circumstances described by each the ferry’s crew and passengers alongside CCTV, and identification of the victims, that allowed them to deal with the incident as a homicide case.

Mr Johansson informed Fakt: “I would like to emphasise that there is no suspect and we do not intend to charge anyone.”

When Mr Johansson was requested if the explanation for the shortage of charging was as a result of the mom was lifeless, he reportedly minimize the dialog brief.

Mr Johansson mentioned he couldn't reply. The investigation continues.