What is the test for suppressing evidence that was seized during a search?

"Counsel for petitioner relies on United States v. Evans, D.C., 194 F.Supp. 90, as demonstrating that the evidence seized should have been suppressed. In the Evans case the trial judge on disputed testimony found the search without a warrant as unlawful and suppressed the evidence. This was a finding in the early stages of the criminal case. Here the petitioner has the burden of establishing the illegality of the seizure. While the officers were lawfully in the residence they saw an object that had been taken. They then placed petitioner under arrest. I must hold the search was incident to the arrest and there was no denial of due process in permitting that evidence to be received."