Perry Mason used standard police work with no computers and blatant lies to get into private homes (no warrants from a judge) 'I'm from the phone company to check your phone' is how they got inside homes.
Mason and staff pretended to use finger prints but that was also a lie. Real finger print collections at the time were only available on cards. In San Francisco, in 1958, the finger print file had less than 5,000 cards,only people who had been arrested and finger printed. That didn't change until 1983 when finger print files on computers were introduced.
Perry Mason had one sidekick and an office staff; they got along well. Mason gave the orders. Mason solved cases by getting the guilty party to confess on the witness stand.
Today, there are nearly a dozen detective stories on primetime TV (NCIS, NCIS-LA, CSI, CSI-M, CSI-NY, Bones, Numbers, Lie to me, Mentalist...etc).
The one thing that identifies all these detective stories is that 90% of the action takes place as drama (and melodrama) between the staffers, staffers and management, and inter-personally between staffers.
That, folks, means that modern television detective stories are really about management. Why?
Because 90% of all working Americans spend most of their life in a managerial environment. Managerial as opposed to industrial, farming or sales.
Back when Americans worked in an industrial production environment the main stories were about rugged cowboys surviving lonely hardship. Jane Tompkins in West of Everything explores that subject.