How to see certificate for intermediate CA in Keychain?
For any Stored certificate, using Keychain Utility:

Open Keychain Utility, choose any certificate, double click it, select Detais:



The certificate will popup up, click on Details triangle.



Look for the issuer on the info below:



Here is the same certificate showed above, with the window extended to show full information: (NOTE: this osu.edu certificate is EXPIRED, so it is shown as "not trusted", but its issuer chain is present on it, and it is valid [the issuer InCommon CA chain].





Here is an Intermediate CA Certificate stored on my Keychain:



Here is another Intermediate CA Certificate





For any website certificate, using Safari:



After clicking "Show Certificate", folow the same procedure and click on the Details Triangle.