Residents and police have been on edge since October 9, when 22-year-old Benjamin Mitchell was shot to death.
Anthony Naiboa, an autistic 20-year-old who had just graduated from high school, became the third victim when he accidentally got on the wrong bus and ended up in the neighborhood by mistake, police said.
Tampa Mayor Bob Buckhorn told officers at a briefing last month to hunt the suspect down and "bring his head to me".
Police arrived "within seconds" of 911 calls, which were placed before 5 a.m., Dugan said.
"Whoever is doing it, they're familiar with the neighborhood and they're able to vanish very quickly", Dugan said. "I repeat, were are now calling this person a suspect and we need to know who this person is".
"I've come up with four reasons why this person is running", Dugan said last month. University of South Florida Criminology Professor Dr. Kathleen Heide says like other serial killers, this one might be craving attention.
Police are investigating the killing, in the Seminole Heights neighborhood, where three people were shot in 11 days in October.
Tampa Police Chief Brian Dugan says the department has received hundreds of tips in the 24 hours since the fourth shooting death was announced.
The most recent victim of the string of slayings was 60-year-old Ronald Felton, killed at 4:51 a.m. on Tuesday, according to police.
Police spokesman Steve Hegarty said the suspect couldn't have "gone very far, and we're talking to as many people as we can to see what they may have seen".
One question that we had - with as much video as we have, how has the killer not been caught?
Two days later, Monica Hoffa (left) was also shot after getting off a bus.
Early on, police released pixelated photos of a person of interest, a slender individual wearing trousers and a hooded windbreaker who was initially seen walking near one of the crime scenes and then picking up the pace to a sprint. It showed the suspect repeatedly flipping and staring at a cellphone before Mitchell's death.
October 19, Anthony Naiboa, 20, was shot after taking the wrong bus home from his new job.
The murder of Felton has again put the neighborhood on edge.
Street said she has stopped walking to the store, taking the bus or sitting outside to smoke at night. "I can't thank them enough for stepping up".
She said she exchanged text messages with neighbors who, like her, were in their homes looking on as cops investigated the killing.