The Ghost Lock messages are between Summer and "DM". The key is to figure out who "DM" is.

The Ghost Lock messages are sent on September 13th, 2019, and they reference meeting up "tomorrow" (September 14th). Look at Summer's billing records and patient schedule to figure out who she was supposed to see on September 14th.

Also, look for any discrepancies between Summer's schedule and her billing records.

Summer's schedule shows she was supposed to see two patients on September 14th: Damien Maiden and Dorrine Rheyes. We know from the Ghost Lock messages that Summer was also planning to see "DM" that day. "DM" likely stands for Damien Maiden — but that doesn't mean that "DM" actually is Damien Maiden.

Summer's billing records show she wasn't billing Damien Maiden. Why would Summer see a patient, but not bill them? If she wanted to hide her relationship with Damien Maiden, she wouldn't have listed him in her schedule. Yet, Summer was hiding something. What was it?

To figure out what Summer was hiding, examine the orange figurine from the Part 2 Evidence bag. If you're not sure where it came from, read the Part 2 letter from Stephen Corbin and/or the Part 2 Evidence Inventory list.

Medina dropped the orange figurine on her way out of the police precinct. The figurine is important. To figure out why, read Summer's blog posts and look for a connection to the orange figurine.

Summer's "First Date" blog post describes a date Summer had at a board game cafe. Summer mentions she and her date both took "souvenirs" from the date. The post includes a picture showing an orange figurine — the same one Medina dropped at the police precinct. The figurine was Medina’s "souvenir" from the date.

Summer’s blog mention more dates with Medina. We can infer that Summer and Medina were dating, and Summer's appointments with "Damien Maiden" were a cover for their affair. Summer blocked off time in her schedule to see "Damien" (aka Medina), but Summer couldn't exactly bill Damien for these "appointments" — because he didn't exist!

Medina is "DM" (i.e., "Damien Maiden").

If "DM" is Medina, then who is "G"? Read Medina's witness statement.

If you're not sure who "H" is, think about the people in Summer's life.

In her witness statement, Medina says she has a husband named Gerry. "G" is Gerry.

Answers

"DM" is Medina.

"G" is Gerry, Medina's husband.

"H" is Harrison, Summer's husband.