What With?

This frog is coming with me, says Victor.

No! cries the Kroombit tinker.

For further questioning, says Victor.

Wait, says Arthur. 

He calls Gaius.

Arthur! says Gaius. Are you still following the tinker?

I was, says Arthur, until I found her.

So you've found her, says Gaius. Where are you?

In Florence, says Arthur. We came on the train.

Whatever for? asks Gaius. 

To get a confession from Nicolo, says Arthur. 

You needn't have bothered, says Gaius. 

She wanted to do it, says Arthur. But now there's a problem.

Yes, says Gaius. She's in Florence.

Not just that, says Arthur. She's been arrested.

Arrested! What for? asks Gaius.

Wilful damage to the floor of the Cathedral de Santa Maria Fiore, says Arthur. But we're lucky. 

Lucky? says Gaius. Go on.

The arresting officer is Victor, says Arthur. 

Victor taps Arthur's shoulder.

Here they call me Vittorio, says Victor.

He's here on an international officer swap, says Arthur.

Put him on, says Gaius.

Arthur hands Victor the phone

Pronto! says Victor.

Victor! says Gaius What's this I hear about you arresting the Kroombit tinker?

Damage is damage, says Victor. I can't let it go.

That frog is endangered, says Gaius. And I am responsible.

Surely not, says Victor. Wouldn't it be disappearing habitat, or chytrid fungus?

Responsible for HER! says Gaius. I allowed her to come as house mother for the pobblebonk team, who unfortunately are no longer with us.

Oh? says Victor.

Not her fault, says Gaius. In fact I believe she has obtained a written confession from the real culprit.

I'll follow it up, says Victor. But for now, she remains in my custody.

What has she supposedly damaged? asks Gaius.

She has chipped a mosaic tile, says Victor.

What with? asks Gaius.

Victor has not got this far.

He looks at the tinker.

She has soft body parts.

She is holding a soft oily rag.

How might she have done it?