I do not see this manga ending on a positive note. For now, Spica only kills those who committed actual crimes which entail killing innocent people. Usually in scenarios like this, the killer starts getting used to the feel of killing. They will grab any opportunity or excuse to kill. Like she might start going after people who committed ordinary crimes and kill them to satisfy her urges. Then we have the case of that detective. He has already figured out that something's wrong with Spica and he's quite close to figuring her out completely. How would she keep him quiet? Would he let her continue doing her work in the shadows to snuff out the criminals or would she put him out too? Then there's her classmate too. That boy's also got a bright mind.
Anyhow, Spica herself might be killed in the end as well. Like if people got to know that she can read minds, they could easily alter their thoughts or put fake thoughts in their head to throw her off completely.
Excited to see how this ends.