Usually the property owner
In practice, remediation of a unit after an unattended death, hoarding condition or waste contamination is arranged by the owner or property manager, who may then pursue recovery through a deposit, an estate or insurance.
Do not send maintenance
Blood, waste and needles are not maintenance tasks. Sending untrained staff creates exposure risk and liability.
Documentation
A written scope and record of the work performed helps when discussing the loss with owners, insurers or an estate.