Anna Kepner's grandparents Barbara and Jeffrey were on the Caribbean cruise with her father, stepmother and siblings when she was found dead under a bed

The grandmother of Anna Kepner says her stepbrother “had demons,” even before he became a suspect in the 18-year-old’s death aboard a Carnival cruise earlier this month.

Joel Leppard, managing attorney at Leppard Law Criminal Lawyers, discusses the latest court documents and filings related to the death investigation of Anna Kepner. Leppard is not directly connected to the case.

In a petition filed in a child custody case, Thomas Hudson, the biological father of Anna's 16-year-old stepbrother said the teen is a "suspect in the death of the step child during the cruise," according to a court document obtained by PEOPLE.