The cops assume semen, but the tests bring nothing back.
Its a mystery goo, and nothing good happens when mystery goo is involved.
Dark Uncle is a much more contemplative episode than last weeks two-parter.

Credit: Bob Mahoney/HBO
Nothing feels real, and yet you feel the weight ofeverything.
Certainly, the events of this episode support that.
Then theres Jessa Maitland, Terrys youngest daughter, who keeps seeing The Man in her bedroom.
Theres no escaping the darkness here.
Things only get stranger when Ralph is presented with new evidence from the barn.
There are two sets of fingerprints on the belt buckle.
The thing is, both sets are a match for Terry Maitland.
Terry young, and Terry ancient, as they put it.
Its just another puzzling bit of evidence that suggests the deceased Terry Maitland isnt theonlyTerry Maitland.
Because nothing makes any sense, Ralph asks Pelley and Howie to help him out with the investigation.
Pelley and Howie know just the person to do it, too.
Shes a human-computer, a unique person as Ralph says.
Now, she gets to be who shes meant to be.
A worker at the facility caring for Terrys elderly father was charged with murdering two young girls.
Something is definitely off because the episode ends with Jack muttering to himself.