I am looking for a way to track prior ownership of a jet engine to confirm I am buying from the holder of record. Does such a database exist?
This information is not kept in a centralized public database. Manufacturers will also be unlikely to be able to answer such a query because they don't normally keep track of the transactions in which the ownership of the engine changes hands, except maybe indirectly if the engine has been under a continuous maintenance contract with them. I also doubt they would make this information publicly available even if they had it. This data is supposed to be kept for each engine in the engine log.
You may be able to indirectly determine that an engine has been with the aircraft for some time by requesting a CD from the FAA with the records of the aircraft in which it is installed, but that would also be a longshot.
If you are just buying an engine as a spare or a replacement, you should closely examine the engine log anyway. If chain of ownership is not clear from the log entries, or if there are unexplained gaps in the logs, then you can decide if you want to proceed with the transaction.