SSBI TS Level Investigation for High Public Trust Position?

I was recently offered a job as an Immigration Services Officer for USCIS under DHS. The job application says it’s a High Public Trust position, but others that are current Immigration Services Officers told me that the investigation requires filling out a SF-86 form and is a full on SSBI mirroring that of a TS clearance…just adjudicated as a High Public Trust clearance. “It’s like they give you a gun without the bullets” one person said.

Does this basically mean that the investigator would do everything in the spirit of a Top Secret clearance investigation?

Also, does anyone know any specifics about how USCIS sees certain issues on the SF-86 form? I’m a non-competitive candidate and I’m afraid that if I don’t get an interim I will have my offer pulled. I had an alcohol related incident in college (six years ago and no police involved) and I’m admitting to using marijuana three times and adderall once during this time. Basically, drug use over 60 months ago. Everything else is clean.

Assuming I utilize the extra comment space in the sf-86 form, is it possible to mitigate these incidents from that long ago if I elaborate on the incident and my mitigating factors? (young college kid, experimental use in social setting only, matured over the years, willing to sign intent form to never use again, etc.)

I know it’s foolish to ask a yes, or no answer on this because everyone’s case is different, but just by a gut reaction, is an interim an unlikely thing to get? And once again, will being non-competitive candidate make me easily disposable?

Thanks!

Drug use over two years ago is pretty much a non-issue as long as you are not applying for an armed law enforcement position or your drug use included selling. I know that is a very broad statement that some will challenge but I think it is fairly accurate.

I don’t think there’s a need to go into detail on your forms as far as mitigating circumstances, you can go into that during the interview.

If you got a job offer and are filling out forms, why do you say you are non-competitive? Sounds like you received a tentative/conditional job offer and now you just need the clearance.