When a biohazard happens in a rental, two insurance policies, a lease, and state law all meet in one room. The general rules:
The working default: remediation of the structure is the property owner's responsibility — habitability duties in most states require the landlord to restore the unit to safe, livable condition, and their property insurance is the usual funding source. The tenant's belongings are the tenant's (or their renter's policy's, or their estate's) issue. Leases can shift some costs — e.g., damage caused by the tenant — but they cannot shift the habitability duty itself in most jurisdictions.
After the scene is released by authorities, the landlord generally arranges and fronts structural remediation, then looks to (in rough order) their insurer, the tenant's estate (for damage attributable to the tenant, where the lease and state law allow), and the security deposit — with deposit deductions for biohazard damage being a frequent dispute that state deposit statutes govern. For deaths caused by crime, a victim compensation claim by the family may cover some costs. Landlords should document everything and use a professional service; assigning maintenance staff to clean a death scene invites OSHA trouble and worse.
Hoarding raises a parallel issue: it is often tied to a recognized disability, so eviction-first approaches can collide with fair-housing law — remediation plans and reasonable-accommodation processes come before lockouts. Drug contamination (see the meth lab guide) can carry state-mandated cleanup standards on the owner. Finally, several states require disclosing a death in the unit to prospective tenants or buyers for some period — check your state; when in doubt, disclose. This page is general information, not legal advice; deposit and habitability rules are state-specific.
Often partially — for damage beyond normal wear attributable to the tenant, subject to state deposit law and itemization deadlines. Habitability-level structural remediation is usually the landlord's cost first.
Some states allow lease termination for crime victims (especially domestic violence); otherwise it's negotiation. Many landlords agree to termination after serious events rather than litigate against a grieving family.
State-dependent: some require disclosure of deaths within a set period, others only require honest answers when asked. Lying when asked directly is a misrepresentation risk everywhere.