The Missouri in the Civil War Message Board

Where to find Gratiot Street Prison Records

I am searching for info on Thomas Erastus Lasswell/Laswell
He served Co I 26th TX Cav CSA. I have his papers and per a report dated 12/4/1863 he had deserted back to Walker Co TX(where he was living in 1860 and where his wife and dependents were recorded living on an 1863 indigent families of CSA soldiers list).
Thomas and his parents were in St Louis MO in 1850, mothers family lived around Washington and St Francois Co MO. Had an aunt and uncle Joseph and Sarah Wildman who had to go to Gratiot St Prison in March 1865 and take the oath and were quickly released. Per a family story it was because her nephew Ben Lasswell, a confederate soldier, had visited their house.
I searched the MO Provost Marshals index and found a listing for Thomas Lasswell.
I got back the letter that he wrote to Col Darr who I assume was Joseph Darr.
Sept the 22nd 1864
Gratiot St Prison
Col Darr
I had my trial the 2nd day of this month and have not heard any thing from (unreadable). I wish you would if posabel let me know something of it.
Respectfully yours,
Thos. E. Lasswell
(Two lines of unreadable writing that don't appear to be his writing)

Any Gratiot experts out there who know if/where I'll be able to get info about his 9/2/1864 trial. I didn't find his name in the online list of prisoners and would love to know why he was there and for how long.