Aniah Blanchard had been missing since October 23.

(CNN)Just one day after remains found in woods in Alabama were confirmed to be his missing stepdaughter, UFC fighter Walt Harris posted an emotional tribute to her on Instagram, calling his pain "unbearable."

Aniah Blanchard, Harris' 19-year-old stepdaughter, had been missing since October 23 after last being heard from in Auburn, Alabama. Harris was active on social media during the search for Blanchard, raising awareness about her disappearance with the hashtag #FindAniah.

But on Wednesday, when Auburn Police identified remains found in the woods, the search came to an end. Harris expressed his grief in the post, calling Blanchard his biggest fan.

    "My sweet baby girl... I just wanna thank you for helping me change my life for the better... For teaching me how to be a man and a better father! For being my biggest fan win, lose , or draw! For always knowing what to say to put a smile on my face and lift me up when I was down and wanted to give up," he wrote.

    "This pain is unbearable... I know you want me to be strong but it so hard baby it so hard. I'm gonna find away I promise you I will. Right now nothing makes sense and I'm so lost. I just want you back. I hope I made you proud... I'm gonna keep going daddy just needs time. I love you so much."

    The case has been upgraded to a homicide investigation, according to authorities. The cause and manner of Blanchard's death have not yet been confirmed, though three suspects have been arrested in connection with her disappearance.

    CNN's Jamiel Lynch contributed to this report.