Initial post-mortem tests for a teenage couple found dead at a holiday park are 'inconclusive', police have confirmed.
Cherish Bean, 15, and Ethan Slater, 17, were found at a rental property at Little Eden Holiday Park in Bridlington, East Riding, last week.
Humberside Police said further testing is required to determine how the pair died, but said carbon monoxide poisoning remains the 'primary line of enquiry'.
Three men who were arrested on suspicion of gross negligence manslaughter have been released on bail.
A cordon remains at the site while investigations into the deaths continue.
DCI Ben Robinson said: 'I can now confirm that post-mortem examinations had taken place yesterday (Sunday, 22 February) which have returned an inconclusive result, and further testing is required to determine the cause of Cherish and Ethan's death.
'This outcome comes at what is understandably an extremely difficult time for their families, and our thoughts remain firmly with them as they continue to grieve the loss of their loved ones.
'They are being kept fully informed of all developments and continue to be supported by specialist trained officers.'
Cherish Bean, 15, and Ethan Slater, 17, died at Little Eden Holiday Park in Bridlington
Cherish Bean's mother said she will 'never be the same' following her daughter's death
He added: 'This remains a highly complex and multi-layered investigation, and I can now confirm the 27-year-old man who was arrested on Saturday, 21 February, in connection with our enquiries has since been released on conditional bail. The two other men who were arrested, aged 33 and 42, also remain on conditional bail.'
In a tribute to her daughter released by police last week, Cherish's mother said she will 'never recover' following the tragic news.
She said: 'My girl, my world, my love, my everything.
'My perfect girl, my angel, has left this world and we are broken as a family. I am broken as a mother, and I will never ever be the same again.
'If you know me, I live and breathe my babies, and we were away for a few nights making the best memories ever. We have had the best life together and it has been ripped from under us.
'There are no words, I am shattered and will never recover. Hug your children tonight you do not know how lucky you are.
'Ethan, bless you darling, such a good boy with a kind heart and I loved you like my own.'
Ethan’s grieving mother paid an emotional tribute to her son as well as his girlfriend Cherish.
She wrote: ‘Ethan was the most beautiful young man to walk the earth. He was generous, loving, charming and kind.
‘He would help anyone and was a strong family man. He took care of himself and loved his mum, stepdad, brothers and sister.
‘There’s not one person who would dislike him even if they tried. His smile was contagious, and he could light up any room he walked into.
‘Ethan, you will always be remembered for the amazing young man you were, and the one you were destined to be. We hope you know how loved you are our boy, rest well and keep the table warm for us up there.
‘Cherish was the apple of Ethan’s eye; everyone could see how smitten they both were. She was beautiful, elegant, and made Ethan happy. We know you will keep each other young and safe.
‘Look after each other. Rest in peace.’
Ethan's father added: 'I am a broken man without you son. I will love you eternally my boy. You were taken way too soon from me. Love you always.'
Police said they are continuing to investigate and said carbon monoxide poisoning 'remains a primary line of enquiry'
DCI Robinson said the police will continue to investigate the cause of the young couple's deaths.
He added: 'I would like to offer my reassurance that this update does not represent the conclusion of our enquiries and there is significant work progressing simultaneously, including specialist analysis, searches of the premises, and the extensive review of all the information collated in coordination with partner agencies.
'While the medical cause of death has not yet been formally confirmed, carbon monoxide poisoning remains a primary line of enquiry. We are carefully reviewing and analysing all evidence gathered to ensure we establish the full circumstances in the lead up to and surrounding these deaths.
'The cordon at the site remains in place while further specialist work is undertaken. We continue to work closely with the Health and Safety Executive, Humberside Fire & Rescue, and East Riding of Yorkshire Council.
'We understand the significant impact this incident has had on the wider community and thank residents for their cooperation through our continued commitment to conducting a thorough investigation.'
A spokesperson for the Health and Safety Executive previously said: 'We are aware of the incident and assisting Humberside Police and East Riding of Yorkshire Council with their enquiries.'