Today marks the first anniversary of the deaths of three teenagers in a crush at a St Patrick's Day event in Co Tyrone.
Lauren Bullock, 17, Connor Currie, 16, and Morgan Barnard, 17, from Dungannon in Co Tyrone, died near the entrance to the Greenvale Hotel in Cookstown.
More than 600 people gathered outside the hotel disco before a crush in which the three teenagers died.
To date two people have been arrested and a further eight people have been interviewed under caution. The two people arrested have been released pending a report to the Public Prosecution Service.
PSNI Detective Chief Inspector Eamonn Corrigan said: "One year on from the heart-breaking events, our thoughts remain very much with the families of the three teenagers who sadly lost their lives at the St Patrick's night event, and also with their friends, anyone who witnessed the tragedy unfold and the wider community.
"We do not underestimate that today will be extremely painful and traumatic for the families of Morgan Barnard, Lauren Bullock and Connor Currie and I would like to reassure them that our focus remains firmly on trying to find answers for them.
"We remain in close, regular contact with these families providing them with updates on the progress of the investigation, which is one of the largest undertaken by the PSNI, we will continue to offer them personal updates at any time of their choosing.
"Our dedicated team of detectives continue to work diligently and this major investigation is advancing.
"However it will take time as it is complex and involves a significant number of witnesses and substantial amounts of evidence to be assessed and progressed."