Clue #1:

The most obvious one. Einhorn in German means Unicorn, or more plainly "One Horn". For my most inept readers, that name betrays the existence of her phallus. This lends credence to the next one.

Clue #2: A very sneaky use of foreshadowing: When Ace rejected Einhorn's advances, saying " whip down boy!"

Clue #3: This one would have been a dead giveaway if you were some idiot savant of history. Ray Finkle is an allusion to Frank Finkel, the man famous for claiming to be Custer's only survivor of the Battle of Little Bighorn. Get it? Lois Einhorn. Little Bighorn.

Clue #4: Ace subconsciously knew shlee (that's he/she) was conniving and falsely ignorant. Shlee tested Ace by calling the dolphin a porpoise to hear his reaction and judge whether or not shlee was his suspect, a reply which Ace concluded with "That's what turns me on about you, your attention to detail." Einhorn did take the words "turns me on about you" to mean that shlee is a suspect, and "attention to detail" as an implication of shlee being one who schemes. The clue lies in Einhorn's prompt and reaction as we are misdirected to think that this is a response of humiliation instead of culpability and by this the ideal detective would've solved the mystery by now.