Security Deposit Return

[Nicholas Denning]

Hey guys. My sister was renting an apartment in downtown Denver. Per the lease, the leasing company had 60 days to return her deposit. She just received a letter from them, 71 days after stating that they are not only keeping the deposit, but she owes them money. Can they do that past the 60 days? And if so, do they have to have documentation on the supposed damages they took out of the deposit? Thank you