Someone approaches the party with a plan for fortune: Stealing a basilisk egg. He found one but he needs help.
Indeed, there is a lair and there is are a few eggs and it is doable.
Once the deed is done, the party receives a nice sum.
Later, the party sees that either the egg was sold to, or the character was, a sculptor. Coincidentally, a venerable one and an expert in life-life statues.
In truth, he “buys” criminals, especially violent ones that no one wants to deal with or offers homeless people an amazing week for their services or simply offers to pay people, again, for services. Especially those who may want to provide a good life for their loved ones. He does deliver on the promise since he is paid handsomely for his statues.
His method is relying on the basilisk he grew himself. He uses his invisibility wand on the creature, which waits patiently. When the sculptor signals after dressing and positioning the model exactly as he wants, the creature will come out of invisibility and petrify the victim before they even have a chance to react.
Party can see his current basilisk: Old and likely close to death.
If confronted, the artist will likely get the basilisk to attack. Without its defence, he’ll explain that he really used to sculpt perfectly but after some attack or health issue his hands were damaged and he lost his ability. He really raised a basilisk as an exotic pet so he decided to use it while getting rid of criminals. When he couldn’t find criminals, he went with homeless who would choose to live an amazing week that they would otherwise never be able to, before “liberating them” from their misery. One person who actually witnessed what he did volunteered for it, in return for the sculptor providing for his family. After that, the sculptor conveniently assumed others would do the same and asked some people if they’d sacrifice much in exchange for their family’s well-being but not properly clarifying what the sacrifice is.
He’ll say being caught is a wake up call and that he will only do it to criminals or make sure to explain clearly what he does and offer a lot of gold to the party. Surely it’s a good thing to get rid of criminals: They’ll commit crimes when they are out anyway and they won’t drain resources while they are being kept in a prison.
How does the party react? Do they extort him further? Do they accept? Do they kill him? Bring him to justice? Use him to handle some of their worst enemies? What about the current statues and their loved ones? Do they inform anyone? Go after them with stone to flesh scrolls?
This could be a side gig, maybe the party won’t care that much or it could be a whole adventure trying to find and reverse as many statues as they can.