Crewe, Cheshire, England. A blacksmith by trade, he was working with the Grand Junction Railroad Company. He was a mormon elder and had baptized several people while in Crewe, but one baptism did not go as planned.
Jonathan was baptizing Sarah Cartwright, the wife of his friend and co-worker, when the river bank gave way and the two of them fell and were swept away into the water.
Jonathan lost hold of her and Thomas jumped in and was able to grab hold of her petticoat, but the current was stronger and separated Sarah from her garment. They were both swept away down stream. Pugmire was pulled from the water and they found Cartwright about 100 yards down stream, but poor Sarah drowned.
Cartwright and Jonathan were both arrested for manslaughter and sent to Chester Castle until their trial. They were both acquitted.
By all accounts Sarah Jane Cartwright was an unwilling participant. The only reason she gave in to her husband's demands for being baptized was so he would quit pestering her about it. There are several accounts of the incident in newspapers from England, Australia, Wales, Scotland, and Ireland. These same articles were printed in some U.S. papers.
Jonathan Pugmire, jr gives his own account of what happened years later and it is recorded in the church history:
The British articles present a clear account of what happened, but it's obvious you need to look past the obvious bias towards the Mormons. Here is an example from the Leeds Intelligencer, December 9, 1843:
There is an excellent article about the tragedy at The Keepapitchinin. I totally agree with his viewpoints.
I have known about this incident for quite a while, but imagine my surprise and horror when I discovered that these two characters were involved in the Mountain Meadows Massacre!