On DB2, who updated a record and what did the record look like before the update?
I've tested two tools that can provide info about transactions including when, who, using which computer and application

ApexSQL Audit creates auditing triggers for you, so if you're not up to coding and creating triggers for each of your tables, this is an option



It has 2 built in reports, and the good thing about it is that it saves all captured transactions into 2 tables, so you can run queries against them and extract any info you need



Unfortunately, it can't replay the transactions

Another one is ApexSQL Log. It reads transaction logs and trn backups, so the database has to be in Full recovery model. Besides the data transactions, it also tracks schema changes (create table, alter function, etc) and it can replay transactions