Read the suspected burglary report carefully. Are there any suggestions about what Luka might have stolen from Summer's house or things that look out of place?

The suspected burglary report mentions that Summer said it looked like her jewelry cabinet had been rifled through.

Read Summer's blog posts carefully.

Read Summer's blog post "Happy Birthday to Me!" Does anything in the post look familiar?

Summer's blog post "Happy Birthday to Me!" shows a picture of an infinity bracelet that Summer says her co-workers gifted her. The same bracelet was found in the blue envelope that Jessica left in Summer's office.

We know Luka broke into Summer's house and likely rifled through her jewelry cabinet (mentioned in the suspected burglary report). 2 month later, Luka got Jessica to leave an envelope with Summer's bracelet in Summer's office, so we know Luka had Summer's bracelet 2 months after breaking into her house.

We can infer that Luka stole Summer's bracelet.