Some of the 89 prisoners currently on the loose from Ford open prison have been missing for years, Sussex Police have said.
The force said the average number of prisoners who have absconded from HMP Ford in recent years stands at 23 annually, but that currently 90 are at large.
A police statement said they found in November that there were a number of missing inmates whose cases were not being reviewed regularly.
It said: "A dedicated team was set up to review each of those cases to try to identify lines of inquiry that we could follow to try to track the absconders down."
More top news
After seven days of spectacular chaos, the fog is now starting to lift. Tom Bradby takes a look at what could lie ahead for the UK.
Bank of England governor signals possible interest rate cut saying "monetary policy easing will likely be required".
A look at how Mouquet Farm, north of Pozières in France, became a pivotal battleground during the Battle of the Somme.