No unfortunately that did not solve the problem. I've called removeDatabase() but it still keeps a lock on the file. To verify that I'm using it correctly,

If I add a database like this:
QSqlDatabase dbProject = QSqlDatabase::addDatabase("QSQLITE");
dbProject.setDatabaseName(active_db_file);

I remove it like this:
dbProject.close();
QSqlDatabase::removeDatabase(active_db_file);

Is this correct? If so there is something holding onto the database that I need to find...