Forum game: Mimi can't do without a mystery...

I think in all our forum games, we’ve either reached the “Q” or the “X” by now. Anyone up for a new game? Let’s tell a mystery story. Everyone writes one sentence, and by the end, hopefully we’ll know who the culprit is :-)
I’ll get things started.

Late one evening, when Berta came home exhausted from her job as a waitress at a small downtown restaurant and unlocked her apartment door—her mind already on the scarf she wanted to knit a few more rows of before going to bed—she froze in shock, because there was a shoe under her sofa that definitely didn’t belong to her.

She simply didn’t wear pink high heels—at 1.88m, she was already taller than almost every man she knew.

Cautiously and with her heart pounding, she closed the door again and rang her neighbor’s doorbell—a neighbor who had often come to her rescue in times of dire need.

Berta pressed her ear against the door and listened. 

She then notices that the front door is open. Anxiously, she calls out softly, “Kai-Uwe… are you there?” but hears nothing. Carefully, Berta opens the door a crack—just enough to see inside the apartment.

The living room was a complete mess—and Kai-Uwe was known for being so meticulous!

And there was a pink high heel lying there, too… she’d seen K-U in plenty of clothes that were unusual for men, but never in high heels.

The only thing missing was any sign of Kai-Uwe himself, which was rather unusual for that time of day—or rather, night.

Berta found the whole thing very strange, so she took another step
into the apartment, and that’s when she heard a soft moan coming from the bathroom....... 

Berta wondered what to do, because it was all very strange—especially the mysterious high heels, which, being size 43 and pink, were rather unusual.

Then the moaning was heard again, this time a little louder.

Berta briefly considered calling the police, but then she mustered all her courage and walked toward the source of the moaning.