Where is the link between JobID and StaffID of person who completed the install

Hello,
One of our programmers is accessing the API's to download the data for us to aid in our reporting requrements and we are having issues trying to find the correct data required.
The Job Master file stores the job details and the JobUUID identifier, but what we require is the file and the join to the file that can identify the staff member/user who performed the install.
The JOBACTIVITIES table has a list of activities and the StaffUUID against the jobUUID but these can have multiple people against the job - we need the flag that identifies which staff member did the install at the job.

For example in the Job Activities for job 455
we have the following staffid's showing activity -- How do we identify the one who did the install, what other fields/files do we need to use?

5DEDAEF7-DAA7-4C6F-9A8D-301C7D8D00AB
0B0DD66F-A1F0-418C-A6A0-32855E374CCB
5B998FA5-FA02-4169-98FF-72B67C9D6F4B
C3A9EB96-4256-43C4-A304-B1183382F0BB
EBBB6749-A894-402F-AD74-B8A30583B09B
5BA09A04-D614-4790-963A-D5DA66E989DB

Thanks