Inmate 98639 was an Undine, a prisoner being held at Facility 4028 in 2409.
On stardate 73967.3, it was discovered by Starfleet, posing as Captain T'Vix of the USS Cochrane. "T'Vix" and two other officers were removed from duty. (STO website: The Path to 2409)
By 2409, it was imprisoned at Facility 4028. During a Jem'Hadar attack on the facility, it was freed and fought to escape before being subdued. (STO mission: "Facility 4028")