Leah Croucher's dad John made a heartbreaking post on what would have been his daughter's 23rd birthday, just months before human remains were discovered at a house.
She was just 19 when she vanished in 2019, with nobody knowing where she was going and there was never a confirmed sighting of the missing teen.
Human remains were found this week at a house that was on her route to work in Milton Keynes, just half a mile from where she was last seen.
Police launched a murder probe on Wednesday after a rucksack and other personal items belonging to Leah were found, although no arrests have been made.
On August 14, Leah's dad John posted a tear-jerking message to his daughter, asking where she is and whether she is safe, adding that looking at photos of her 18th birthday brought enough pain to the surface "to drown us".
He said: "Your birthday is here again Leah. But again you are not.
"For the fourth birthday in a row. You're 23 now, if you're out there somewhere.
"Happy birthday seems a pointless and meaningless phrase as we don't even know if you ever get to read our posts.
"For us the day is empty, a non event.
"We should have been out buying balloons and a cake, ready for a family meal out. You never wanted a party, always a low key event preferred.
"Memories of your 18th birthday came up on FB a couple of days ago. Looking at them should bring joy, a chance to reminisce. Instead, we avoid looking at them, the pain swells up to the surface, enough to drown us.
"Where are you sweetheart? How are you? Are you safe? Do you realise how much heartache and despair everyone you have ever known feels at your disappearance?
"We all miss you too much. People are still looking for you Leah. Looking for a clue as to what happened.
"Tomorrow is exactly 3 years and 6 months and one day since we heard your laugh, your voice, since we said goodnight.
"Since we saw your beautiful face and your amazing smile. That's too long ago. Please come home so we can have a hug.
"All our unconditional love forever, mum and dad. XXXXXXXXXXXXXXXXXXXXXXX"
Leah Croucher's family were hit by a second tragedy following her disappearance. Her brother took his own life, after feeling "hopeless" and "lost".
Haydon, 24, died after telling a therapist he was struggling to cope with his sister's disappearance.
Haydon was found dead in his flat in Bletchley, nine months after Leah vanished.
He was discovered by his mum Tracey Furness and sister, Jade, before he tragically later died in hospital.
Police had started searching the house where remains were found after a tip-off from a member of the public on Monday.
Thames Valley Police said: "During our forensic examinations at the scene in Milton Keynes, we have identified human remains.
"The forensic examination continues and will do for some time. It is likely to take some time to formally identify the deceased.
"Leah's family continue to be kept informed and updated. We ask the media to respect their privacy at this very difficult time."
Detective Chief Superintendent Ian Hunter said: "Following a call to police on Monday, we attended an address and located items of concern within the property.
"We are dealing with a very difficult scene but we can now confirm that we have discovered a number of items that are linked to Leah, and as such we have now launched a murder investigation, led by our Major Crime Unit.
"Leah's family have been kept updated and continue to be supported by officers, and we are urging the public and media to think of her family and not to speculate further while this investigation is in the early stages.
"We will provide further updates when we are able to do so.
"There remains a scene watch in place at the address while this investigation continues, and we are committed to ensuring that our inquiries at the scene are thorough."
He said hundreds of officers and staff have worked on the search for Ms Croucher in the past three-and-a-half years, scouring 1,200 hours of CCTV and carrying out 4,000 house-to-house inquiries.
The search for her has involved specialist police search teams, the mounted section, police dogs, the marine unit and the National Police Air Service.
The scene at the house is "difficult and challenging" and "thorough and respectful" searches may take some time, Mr Hunter said.
