Default Permissions On Creation Of New Database

I notice when I create a new database within my SQL Server that the
permissions for the new database automatically adds a user (Who is configured
as sysadmin) with dbo permissions to this database.

Both within the login properties of the select user (User mapping) is listed
as Default Schema, dbo and within the permissions of the database listed as
user with connect permissions.

I have other users configured as sysadmin and they do not get this rights
(They are not expliticly listed within user mapping with dbo or permissions
as user within the database).

I've inherited this system and wonder if the user has somehow changed the
new database procedure so it changes the default permissions of new databases.

Any way to check what he's done, I can see no differences between him and
the other sysadmins but he's definatly specifically listed as a dbo on all
new databases.

Although I don't mind him having access, he's a sysadmin after all, I'd like
to make it uniform thoughout the system, i.e. using the inhertited
permissions rather than specific permissions that seem to be created when the
new database is created.

Any ideas?

Flubster