Child welfare officials have previously investigated a man who killed his mother and 9-year-old niece.
A SWAT team took 23-year-old Jason Rios into custody Thursday after a three-hour standoff at an unoccupied neighboring house. Rios, who suffers from mental illness, also injured another girl in the attack at their New Port Richey home.
Child protective officials had conducted previous investigations regarding the children but said there were no open investigations at the time of the attack. The last investigation was closed over six months ago.
The Department of Children and Families has opened a new case.
Ernesto Rios said he was getting his four grandchildren ready for school when his son attacked the two girls. Emergency workers found 55-year-old Angela Rios dead. Jenica Randazzo died Friday at a hospital, where the other girl is recovering.
Two boys who lived there weren't injured.
