A fight ensued, and Sera accidentally witnessed Serph's true, evil nature, which he had hidden from her.
He murdered Fredrik Nordberg when he began black-mailing Vadenblick, having accidentally witnessed him push his wife off the balcony of their luxurious apartment.
Phyllis makes inopportune surprise visits, and often complains of "a sick headache" after accidentally witnessing a spell in motion.
"I accidentally witnessed someone using it and deduced where it led."
After accidentally witnessing a mafia hit in Chicago, they go on the run, landing in Los Angeles.
"In the Honshu terminal," said Nick, "Susan accidentally witnessed more than she should have."
In the afternoon he'd attended a funeral, or just accidentally witnessed one, hanging back, rather, in the mournerless churchyard, where the graves were flush with the earth.
Meanwhile, on Earth, four human children (three boys and a girl) accidentally witnessed a battle between the Protectobots and the Combaticons.
"You accidentally witnessed the sale of an accordion."