They load Charles onto Oliver's dog stroller and head to the basement to try to repair the leak, but are greeted by Jan with a gun pointed at them. Mabel tackles her (and punches her in the face for killing Tim).

Who Murdered Tim Kono?

The Season 1 ender, titled “Open and Shut,” confirms that Charles' bassoonist girlfriend Jan (played by Amy Ryan) was in fact the neighbor who killed Tim and made it look like a suicide.

Does Mabel know the guy who died?

Mabel Mora (Gomez) knew him when they were kids, when they played Hardy Boys-style sleuthing around the building. Tim was shot, but a toxicology report found he was also poisoned.