Hotel security guards are among 33 people facing charges that they failed to help tourists during 2015's deadly attack on a beach in Sousse, Tunisian officials say.
They are accused of not assisting a person in danger, leading to their death, spokesman Sofian Sliti said.
It comes after a UK judge said the Tunisian police response had been "at best shambolic and at worst cowardly".
The attack by student Seifeddine Rezgui killed 38 people, most of them British.
He opened fire on holidaymakers in the resort of Port El Kantaoui in an attack claimed by so-called Islamic State.
Police officers near the scene ran in the opposite direction to get more guns while he shot sunbathers and threw grenades, the British inquest heard.
Rezgui then went into the Imperial Hotel to kill more people. He was shot dead by police an hour after beginning his attack.
Six security guards from the Imperial Hotel are among those under investigation, Mr Sliti told Reuters.
So far 14 people have been arrested, 12 people are being investigated but are not in custody and seven more are on the run, Mr Sliti said.
The investigating judge ended his investigation last July and the case has been sent to Tunisia's criminal court but no trial date has yet been set, he said.