Yeah, they could and would. They would also examine her clothing and shoes for paint dust/over spray, examine her fingers for signs of paint from the nozzel of the spray can, check her account for paint purchases, and interview the *witnesses* to determine their credibility.
Dunn also gave inconsistent statements during two interviews by law enforcement. Not good.
I would guess she is may very well be in deep sh*t.
Things the police/FBI can find -- matching spray paint mist on clothes, shoes; the can, which was probably found, traced to the store where it was bought and where the clerk or a paper trail may identify the buyer -- if the time of day the purchase was made is known, they will look for suspect's alibi. If the police are even marginally competent, they immediately impounded every campus dumpster and combed the whole place for evidence. They're not dealing with an especially clever suspect.