DURHAM, N.C. — He hated religion. He hated rule breakers. He hated people who parked in his spot.

The man at the center of a case that caused a worldwide furor four years ago over anti-Muslim violence was filled with so much hate that he shot and killed three of his neighbors, all students of Middle Eastern descent, at his apartment complex in Chapel Hill, N.C.

The man, Craig Hicks, pleaded guilty on Wednesday and will serve three consecutive sentences of life without parole for murders that the police initially said stemmed from a parking dispute.

Even so, the case has tested the limitations of the legal system on the question of when a hateful crime becomes a hate crime. Across the country, reports of bias-based attacks are on the rise. But many such cases that get to court are not officially prosecuted as hate crimes, to the surprise and sometimes the dismay of those on the victims’ side, for whom the question can be as much a moral issue as a legal one.

The families of the slain students — Razan Mohammad Abu-Salha, 19; her sister, Yusor Mohammad Abu-Salha, 21; and Yusor’s new husband, Deah Shaddy Barakat, 23 — have repeatedly pressed for a hate crime designation, to no avail.