Police have released the names of the mother and daughter found dead at a flat in Newry on Thursday afternoon.
The bodies of 37-year-old Giselle Marimon-Herrera and her 15-year-old daughter Allison were discovered in the Glin Ree Court area.
The body of a 38-year-old man was also discovered at the property. He has not yet been named.
"My thoughts today are very much with their families and friends who are trying to come to terms with their loss," Detective Superintendent Jason Murphy said.
"Giselle is from Columbia and she arrived in Northern Ireland around four years ago. Her daughter, Allison, was born in Spain and has lived in Northern Ireland since 2017.
"She attended Newry High School and my thoughts today are also with the teachers and pupils who knew her. They too are trying to come to terms with Allison's death.
"I believe that Giselle and Allison were still alive in the early hours of Sunday morning but family members have not been able to contact them since. The exact circumstances of what happened in their home remains the subject of our investigation.
"I would appeal today to anyone who came into direct contact with either Giselle or Allison or communicated with them via text or social media since Friday to contact detectives in Newry."
Police have confirmed that they are not currently seeking anyone else in connection with the deaths.
Initial reports suggested detectives were treating the incident as a suspected double murder and suicide, but this has not been confirmed.
It is also understood that the three victims were known to each other and that they died in a violent manner.
Principal of Newry High School Iestyn Brown said the community was shocked by Allison's death.
"The entire Newry High School community is deeply shocked and saddened to learn of the passing of our Year 11 pupil Allison," she said.
"Allison was a talented, kind, courteous and well-mannered pupil with a beautiful smile. Both staff and pupils are profoundly saddened by her death and she will be remembered with great affection by her fellow pupils and staff alike.
"Our hearts go out to Allison's family circle; they are foremost in our thoughts and prayers at this sad time."
Post mortem examinations are set to be carried out on all three bodies today.
"We are currently supporting the families of those involved as well as Newry High school.
"I would ask that they are given the time and space to come to terms with these tragic events," said Supt Murphy.
"Post mortem examinations are currently underway. I do not yet have any preliminary or definitive causes of death, and I do not intend to speculate about that today.
"While our investigation remains at an early stage, there is no evidence at this time that anyone else was involved.
"This is an unspeakable tragedy and anyone with information should contact detectives on 101."