Under California Civil Code Section 1710.2, if someone dies on the property, it's a material defect – but only if the death occurred within three years of the date you make an offer to purchase or rent the home. Technically, if the property was the location of a mass murder in 1975, the seller, lessor, agent or broker does not legally have to volunteer the information.

However, if the seller or their agent knows of a death that occurred prior to the three years, and you/buyer asks they must disclose. If you don't ask...they don't have to tell you, if it has been longer than 3 years.