FBI released 128 pages of documents, spanning the years 1988-1992, which detailed investigations that were conducted on behalf of the singer who died at the age of 48 on February 11, 2012.
The first case FBI investigated was about an unemployed Vermont resident and US Army veteran who had written 79 letters to the Grammy winner and 16 letters to her family.
He once wrote that he fell in love with the singer, whom he referred to as "Miss Whitney", and praised her as "the prettiest the loveliest and the most beautiful lady that there is" in March 1986.
In the end, the case was closed as the FBI met the fan in June 1988 and he said he would not take any action for he realised "it might hurt her reputation."
In another case, an unidentified person claimed to have Houston's details regarding her romantic relationships and threatened that if she did not pay USD 250,000 in exchange for the juicy secrets, the person would reveal them to public.