Prosecutors explained there was inadequate proof versus a fifth agent.
Individuals named will now have 20 days to respond, and any demo will probably be in absentia.
The Cambridge University student were studying unbiased trade unions - a delicate issue in Egypt.
Italian prosecutors named the 4 suspects - now set to generally be billed - as Gen Tareq Sabir, Col Ather Kamal, Maj Magdi Sharif and Col Hisham Helmy.
There was no fast reaction from Egypt to the Italian allegations.
Egyptian authorities have Beforehand denied that any in their officials were being linked to Regeni's kidnap and murder. They have advised various other explanations - such as that he was the target of the theft by a felony gang.
And on one December they explained they had been "temporarily closing" the investigation into your murder, Using the killer "continue to not known".
Regeni went missing in Cairo in January 2016 and his mutilated and naked entire body was located in a ditch around Cairo nine times afterwards.
The murder caused a diplomatic row in between the two countries, with Italian prosecutors accusing Egyptian officials of seeking to mislead the investigation.
"We now have obtained unequivocal and important proof," Rome Main prosecutor Michele Prestipino advised a news convention home on Thursday.
"For Giulio's murder There's just going to be 1 demo, and it will be held in Italy."
he BBC's Rome correspondent Mark Lowen says any demo will throw a spotlight on Egypt's dire human legal rights record. Egypt's Commission for Rights and Freedoms suggests greater than two,seven hundred people have been "forcibly disappeared" given that 2015.
And it could prompt questions about a rapprochement with Italy's present-day government, which lately approved huge arms income to Cairo, our correspondent says.
What transpired to Giulio Regeni?
The PhD university student disappeared on a research vacation on twenty five January 2016 - the fifth anniversary of the start on the rebellion from previous President Hosni Mubarak, meaning there was a hefty law enforcement presence in Cairo.
An Italian publish-mortem examination uncovered that Regeni had been tortured "in phases" involving 25 January and also the day of his Dying.
His body sustained injuries that confirmed he was beaten with "kicks, fists, sticks and clubs", Which he died from the damaged neck, prosecutors stated.
Egypt has denied that Regeni died in custody Whilst officials have admitted that safety products and services were monitoring him.
Egyptian investigators have Beforehand proposed that Regeni was murdered by a five-sturdy felony gang - and that all of these have been then killed inside of a shootout. Italian officials have branded The concept "implausible".
Italian prosecutor Sergio Colaiocco informed a parliamentary Fee that Egyptian officials had developed "bogus tales... to throw off the investigation".
Other strategies place forward by Egyptian investigators had been that Regeni died in a car or truck accident or even a gay criminal offense of enthusiasm.
His overall body was found out on three February in the ditch because of the side of a street. His mom advised the Italian parliament in 2018 that my sources her son's human body was so disfigured that she was only capable to discover him through the tip of his nose.