Bob once witnessed his infamous pitch that happened fifteen years ago but is now hitting rock bottom.

As it happened, Chastain once witnessed an own goal that would have tragic dimensions.

He'd once witnessed Parnell leaving the dinner table in mid-bite when an idea had struck him.

The latter reminds me of an exchange I once witnessed.

"So I became a believer, having once witnessed it myself."

The writer once witnessed the eviction of a young reader from a London branch library.

I once witnessed the result of a gas attack, you know.

I once witnessed the proverbial sight of a peasant beating his donkey.

I once witnessed the destruction of a small stone house by means of a simple fertilizer bomb.

When the murderer was a kid, he once witnessed his mother's death under a stray bullet from a police officer.