"In the morning," Millicent said. That was when she usually came to the Ministry. Then she had all day to play with her fun new toys and welcome them to Azkaban. She gave an annoyed growl, not directly at Fletcher, but at whoever had said they had seen her. Or, if they weren't lying, at whoever had pretended to be her. "I always come in the morning, and I was in Azkaban all day. The other guards saw me."
And plenty of her victims, too, but they were hardly believable witnesses for an alibi. Either they'd be too scared to say anything against her (if she was lying, which she wasn't) or they'd lie to get her in trouble because of what she'd done to them. "Are you saying someone-- they fucking--" What did they need to look like another person? Was there a potion or a spell for that? The most Millicent had ever been able to manage was being somewhat catlike.