WASHINGTON — Eighteen students at Penn State University were charged Friday in the death of a 19-year-old sophomore who became drunk and fell repeatedly during a fraternity “pledge night” in February. Authorities said the student was left overnight, unconscious and obviously injured, by fraternity members who knew he needed help but failed to seek it.

Eight of the students were charged with involuntary manslaughter — as was the fraternity itself, the Penn State chapter of Beta Theta Pi. The other 10 face lesser charges, including hazing and furnishing alcohol to minors. Prosecutors also contend the fraternity brothers tampered with evidence to try to thwart an investigation.

The Feb. 4 death of Timothy Piazza, an engineering student from Lebanon, N.J., rocked the Penn State campus. The university’s president, Eric Barron, barred the fraternity from the university and imposed strict new regulations on Greek life, including a prohibition on liquor, kegs and all-day parties.