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One of the most interesting parts of Pretty Little Liars Season 4, Episode 3: "Cat's Cradle" was Detective Holbrook's extensive board showing connections and clues between everyone in Rosewood and Wilden. What can we learn from Holbrook's investigative work? We've taken a close look at what his board has to reveal.

He knows Wilden and Garrett are linked. Holbrook is no dummy. Garrett's photo is huge on the board, and Wilden is linked to it in black. Next to Wilden's photo is written, "Was he looking to solve or conceal? Wilden activity continues after Garrett homicide. Complicit? Extortion?" Meanwhile, near Garrett he has written "Theatre mgr. I.D. of Garrett also fits Wilden timeline."

He's also clued into Ali. Clearly, he realizes that Ali's death may play a part in the more recent murders, including Wilden’s death.

What he has on Hanna. Next to Hanna is written "Arrested. No record." Seems like he's sniffing out Wilden's cover up of Hanna's arrest (which, if you recall, Ms. Marin secured by sleeping with Wilden). He also knows that she, like all the Liars, is connected to that infamous shovel. And clearly he realizes her mom has a connection to Wilden.

What he has on Aria. He has a line linking Aria to "other man?" which we're guessing means he has a sense that Ezra exists in her life, even if he's not sure who Ezra is yet. There's also a note that seems to say Aria would "do anything" for Spencer. Interesting. Who knew Holbrook was a Sparia shipper?

What he has on Spencer. He has her linked to a lot of people, including Ali (who weirdly the other Liars don't look to be connected to) and has written "A.D threatened by S.H / S.H threatened by A.D / Power Play? / Most to gain?" He also wrote "Profit / Passion? / Fear?" Spencer was a person of interest in Ali’s murder case, and he clearly suspects our Liar of something.

What he has on Emily. He knows about Caleb and the lighthouse, and has “lighthouse gun” written very large next to her photo.

Other clues. Here are some other things we noticed and are wondering about:

- Why is there a business card next to the shovel?

- What groundskeeper is Holbrook looking for?

- He has a note on Melissa that says "medical records" and "Find doctor." Is that about her fake pregnancy? Something else? (It's also worth noting he has Ian and his "suicide" note up there. This man is thorough.) Holbrook also wrote "too smart to get set up?" next to Melissa’s photo. (Side note: How does Holbrook know more than us after only being in Rosewood for a few days?!)

- Why does he have Wren listed as “Dr.” Kingston  — with quotation marks around the Dr.?

- What does the note "Did 'W' lie about car? Garrett motive accomplice" mean? Is "W" Wilden? Is he wondering about Wilden's missing car?

- He notes he still needs to confirm Jenna's alibi. Interesting. Very interesting.

- He knows about Mike's break in at Garrett's apartment.

- Next to Dr. Sullivan he has a note saying "Sullivan claims privilege for everything," which we assume means she's refusing to release any info on her patients. He also noted, "Why did she [something] after M.V. [we assume Mona Vanderwall] interview?"

What clues did you catch? Did Holbrook's board spark any new ideas for you? Sound off in the comments below!

Find more Pretty Little Liars spoilers here.

Catch the next episode of Pretty Little Liars on Tuesday, June 25, 2013 at 8 p.m. ET/PT on ABC Family.

Rebecca Martin is an editor at Wetpaint Entertainment. Follow her on Twitter @BeccaDMartin.