Character Reference question

A former co-worker of mine has reached out to be a character reference for their clearance hearing. This person is under going re-investigation and has had 2 DUIs that they did not self-report or list on the eQIP for their reinvestigation.

In the context that I knew them the honest reference I would give is that they were a proficient and reliable employee and team lead. And I never witnessed or was told about any issues related to alcohol use/abuse either on the job or off.

So the question is, is it appropriate for me to attend this hearing? Does it pose any risk to my employer? Does it pose any risk to me?