He tried to discover his secrets, but Superman wouldn`t have that. Instead, the Kryptonian sentinel of justice agreed to work with him and the US goverment. This they did, for decades. When they would need him, they would alert him.
Malloy and Superman always had an awkward relationship, because the goverment had done tests on Supes (without him wanting it), and because they wanted to discover his secrets.
As decades passed, Malloy thought that it was already a due time to retire. This he did. He told Superman, that he wasn`t responsible for the tests performed upon Supes. They shook hands. It`s not known if they became friends.