Courtney Anthony Robinson was taken into custody Friday night and has since been handed over to the Los Angeles Police Department's robbery-homicide unit, the Los Angeles Times reported.
Los Angeles Police Cmdr. Andrew Smith said Robinson was questioned overnight about the attacks, but it's "unknown if he will be booked for the attempted murders at this time."
All three of the stabbings, none of which was fatal, involved middle-aged homeless people who were stabbed in the back, Smith said.
The first attack happened on July 3. The second and third attacks happened on Tuesday and Thursday.
Police said "death warrant" notes were found at each scene, but did not give any further details on the notes.