Police have arrested a homeless man they suspect robbed four taxicab drivers over a six-week span in May and June.

The man, 23, was arrested at 2 p.m. Tuesday in front of a Kapiolani Boulevard apartment in Kapahulu within a mile of three of the four robberies. He was being held at the Alapai Street cellblock pending charges on three counts of first-degree robbery, one count of second-degree robbery and one count of violating the terms of his parole.

The four victims, all men, worked for different local taxi companies. The robber used force, threatened his victims and, in three of the instances, displayed a knife while demanding money, police said.

Police said they think the man robbed his first victim, 44, at the 2600 block of Kapiolani near the Marco Polo condominium towers at 9:24 p.m. on May 17; his second victim, 55, on Kapiolani just Koko Head of Date Street, about 1:50 a.m. June 18; the third, 58, near Date and Laau streets about 6:20 p.m. June 26; and the fourth, 53, on Kopke Street in Kalihi at 2:40 a.m. June 27.

Detectives from the Strategic Enforcement Detail of the Honolulu Police Department’s Criminal Investigation Division arrested the suspect by following up on leads developed by the Waikiki District’s Crime Reduction Unit that identified and located the suspect, police said.

The second of the victims is affiliated with TheCab, which, with just under 700 drivers, has the largest fleet on Oahu.

Wayne Greenleaf, TheCab’s operations manager, said each of the fleet’s vehicles has a GPS tracking and alert system that allows drivers to alert dispatchers of an emergency at the press of a button.

In the case of the June 18 robbery, the incident happened so quickly that the driver was unable to press the button, Greenleaf said.

The driver picked up a fare on Hunakai Street in Kahala and was told to go to a location near Kapiolani and Date, Greenleaf said. When the taxi arrived at the destination, the rider put a knife to the driver’s neck and demanded money, he said.

Drivers are warned about the dangers and safeguards they can take to prevent robberies, Greenleaf said. TheCab had police hold a safety seminar about two years ago and it may be time to hold a refresher course, he said.

The company has also looked into the possibility of installing security cameras in each of its cabs but such a measure would cost an estimated $2,000 each, making it cost-prohibitive for many of the independently operated drivers, Greenleaf said.

The suspect has a criminal record and was sentenced to five years’ probation and $13,507 restitution earlier this year after being found guilty of second-degree burglary. Among the charges the suspect is now facing is violating the terms of his probation.