I was a Mexican-American teenager in Texas when Tejano music was at its peak. Selena was the unquestionable star of the genre. For people in my demographic, her death had the impact I imagine John Lennon's death had on the wider population. It was a real punch in the gut.
It came out early on in her career that her family were JWs. They grew up in Corpus Christ, which was a few hours away from my hometown. There were people in my hall who knew people in Selena's hometown who confirmed the rumors. The family was said to have been "inactive" although they were often seen at assemblies.
After Selena died, her father gave many interviews and he mentioned their JW beliefs in several of them. Her brother formed his own band (which is still in existence). His arms are completely covered in tattoos, so I very much doubt he considers himself a Witness.