Hi,
For the tables you mention, it does not seems to be JBPM5. I think in JBPM5 the process runtime is deleted from db when the process is completed.
If you are using jbpm3, this api should help:
http://docs.jboss.com/jbpm/v3.2/javadoc-jpdl/org/jbpm/db/GraphSession.html#deleteProcessInstance(org.jbpm.graph.exe.ProcessInstance, boolean, boolean)
Regards,
Demian