Can Late Fees be Deducted from Security Deposit??

[Ayodeji Kuponiyi]

Hi BP Nation! I hope you all are having a great week. I apologize in advance if this question was already asked. My father-in-law recently retired and relocated back to the Caribbean this past February. He rented out his single family home to a relative (who has taken advantage of his absence by paying rent late since moving in.) 

According to the Lease, the tenant is to pay a late fee of $50 if the rent is more than 5 days late; and then another $20 for each additional day the rent is late. The tenant also changed the locks without the consent of the landlord. My wife has POA (power of attorney) over the property.

My FIL plans to give the tenant a 60 day notice stating he will not renew a lease with them. Great! The problem now is that my FIL doesn't think he can deduct late fees from the security deposit. The tenant has been late since moving into the unit until this present day so the likelihood of receiving the Security Deposit seems unlikely and depending on the condition of the property when he checks it. So there lies the question, can my FIL deduct the late fees from the security deposit? The property is in Pennsylvania. Thank You in advance!