Translate the following English sentence to French:
"It was said that surveillance took place anyway, it was even added, some even said that it was important to have surveillance systems in order to track down serious criminals."
On a dit qu'il y avait de toute manière une surveillance, et on a même ajouté, certains l'ont dit, que, pour traquer la grande criminalité, il était important de pouvoir disposer de systèmes de surveillance.