Prosecutors have requested further investigation into the singer's alleged assault of Rihanna early Sunday morning.

The D.A. confirmed to E! News that Los Angeles police detectives presented their case against the "Run It" singer this morning, but that more evidence is warranted before proceeding with formal charges.

"Prosecutors asked for further investigation," spokesperson Jane Robison told E! News. "No further comment at this time."

Robison did not any details of the LAPD's case against the 19-year-old, who was booked on suspicion of making criminal threats and released on $50,000 bail.

Rihanna, who required hospitalization after the incident, is said to be cooperating with the investigation.

Neither star has spoken out about the altercation, and both have cleared their respective calendars of scheduled appearances.

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