If we put all the letters, the suspected burglary, and Summer receiving the blue envelope in chronological order, we get the following timeline (from earliest to latest):

On June 20th, Luka broke in to Summer's house.

Dante's letter to Luka is dated June 27th, 2019, and it's hidden message is:

How did it go last week? Also any success in cracking J? If she's too hard we can try E instead.

Luka's letter to Dante is dated July 10, 2019, and it's hidden message says:

Good. I got what I needed.

Yes to your second question. I've found her weak spot. She is a risk taker.

We don't need to bother with E because we are set now.

Summer will pay for what she did to you. Nobody locks up my best friend and gets away with it.

The letter found in Jessica's gray bag is dated August 19th, 2019. We can assume this letter was written to Jessica. It's decrypted message reads:

J -

IF YOU CAN'T PAY BY FRIDAY, HERE IS WHAT I WANT YOU TO DO:

GO INTO SL'S OFFICE

LEAVE IT IN PLAIN SIGHT

-L

On August 26th, 2019, Summer found a blue envelope in her office (see the blog post titled "Surprise). There are two sets of fingerprints on the envelope: Summer's and Jessica's. We can assume Summer's fingerprints are on the envelope because she found it and handled it. We can infer that Jessica left the envelope in Summer's office.

Going back to the letter found in Jessica's gray bag, can you figure out who wrote it (who is "L"?) and what the "it" in the letter is referring to (i.e. "leave it in plain sight)?

If you're not sure who "L" is, look at the handwriting in the letter and compare it to other sources of handwriting.

If you're not sure what the "it" in the letter is referring to, think about who "SL" could be.

Quiz: Eliminate a Suspect

Hints: Eliminate a Suspect

Quiz: Eliminate a Suspect

Note: Quizzes don’t always include all relevant evidence. Select all the correct evidence from the list.

Hints: Eliminate a Suspect

Make sure you've decrypted all encrypted notes before reading the hints.

Hint #1

Hint #2

Hint #3

Hint #4

Solution