John F. Timoney, 68, a former New York City police officer who became Philadelphia's police commissioner and an influential figure in law enforcement, has died after a battle with lung cancer.

An Irish immigrant with a colorful personality, Mr. Timoney was Philadelphia's police commissioner from 1998 to 2002. He was regarded as a thinking man's cop with a street sensibility, equally comfortable pushing for the use of data and statistics in how officers were deployed, and patrolling the streets on his bicycle even while atop the department.

Mr. Timoney died Tuesday after being rushed to a Miami hospital, said his younger brother, Ciaran. Mr. Timoney, who was living in Florida, was scheduled to undergo further lung-cancer treatment Wednesday, but suffered complications at home the night before.

"Just a tough guy with a big heart," Ciaran Timoney said of his brother.

Police Commissioner Richard Ross said Mr. Timoney "truly loved policing and certainly contributed a great deal to the profession," describing him as "hard-charging, confident, and very outspoken."

Mike Chitwood Jr., a former Philadelphia police officer and longtime friend of Mr. Timoney's, said, "Outside of my father, he had the biggest influence on my policing career." Chitwood is the police chief in Daytona Beach, Fla.; his father is police chief in Upper Darby.

Mr. Timoney is the second former Philadelphia police commissioner to die in less than four months. Willie L. Williams, 72, an Overbrook native who led the department from 1988 to 1992 as its first African American commissioner, then became the first African American to lead the Los Angeles Police Department, died April 26 in Atlanta.

John Francis Timoney grew up in New York City after emigrating from Dublin with his family in 1961 at age 13. He later joined the New York Police Department and quickly rose through the ranks, eventually serving as a top deputy to then-Commissioner William Bratton, who earned widespread attention for his crime-reduction tactics in the 1990s and has since returned to the post.

In 1998, Mayor Ed Rendell, impressed with the results in New York City, recruited Mr. Timoney to be Philadelphia's commissioner. Mr. Timoney was well-schooled in modern deployment strategies after serving as the NYPD's deputy chief for statistical analysis. The department at the time was pioneering the use of CompStat, a data-heavy method of evaluating police strategies that is now widely used around the country.

Rendell, in an interview Wednesday, said Mr. Timoney's push to rethink how and where to send officers based on data had a lasting impact in Philadelphia.

"He deserves an incredible amount of credit for modernizing the Philadelphia police force," Rendell said.

Homicides during Mr. Timoney's tenure dropped to their lowest level in a decade, something the ever-blunt commissioner - who spoke with a brogue that evoked both Ireland and New York - predicted almost as soon as he took the job.

"If crime isn't going down by this time next year," he told City Council in 1998, "I'll be not only surprised, I'll be very disappointed."

Chitwood said Mr. Timoney valued an educated police force, pushing for officers to earn college or advanced degrees. A police scholarship foundation Chitwood established in Florida was inspired by Mr. Timoney's dedication to education, he said.

Still, Mr. Timoney didn't forgo opportunities to be seen on the street. Rendell noted that Mr. Timoney - a marathoner and rower in his spare time - often patrolled the city by bike. He famously apprehended a purse-snatcher while jogging near Rittenhouse Square during his first week on the job. And on his last night as commissioner, Mr. Timoney, Chitwood, and another officer were on patrol when they encountered a gun battle. As the shooters fled into a nearby home, Mr. Timoney argued about who was going to lead the charge after them.

"The two of us were going to fight about who was going into that house," Chitwood said, adding that he eventually persuaded the outgoing commissioner to let him go in first.

Mr. Timoney's time in Philadelphia was not without controversy. During the 2000 Republican National Convention, police arrested about 400 people, and it later was revealed that authorities had infiltrated protest groups, something Mr. Timoney had denied during the event.

The city faced a number of lawsuits and had to pay an undisclosed total in settlements for wrongful arrests.

Rendell, who was no longer mayor during the convention, acknowledged Wednesday that the approach "probably went too far." The district attorney at the time, Lynne M. Abraham, has since called the arrests "a grave mistake."

After leaving the department in 2002, Mr. Timoney took a job at a private security firm in New York, Beau Dietl & Associates, but maintained a residence in Rittenhouse Square. About a year later, bored by corporate life, he became chief of Miami's police department, which was reeling from a corruption scandal.

Mr. Timoney served there until 2010, earning praise for reforms and updating the department's crime-fighting tactics, but also drawing criticism from civil liberties groups for his aggressive approach to policing large-scale events.

Mr. Timoney later worked with the Ministry of the Interior in Bahrain, where there was widespread civil unrest, and was a consultant for the Camden County police in 2011.

An avid sportsman, Mr. Timoney regularly rowed on the Schuylkill and participated in the Irish Pub Tour de Shore, a charity bike ride between Philadelphia and Atlantic City. In 2010 he published a book, Beat Cop to Top Cop, detailing his life and career.

John Gallagher, an assistant U.S. attorney who worked with Mr. Timoney in New York City, Philadelphia, and Miami, said Mr. Timoney "was one of my heroes," a law enforcement leader who worked to reduce crime and professionalize and modernize each department he led.

"He was ahead of his time in policing," Gallagher said. "I'm sad to say we're not going to see his type again. He was such a force of life. It's hard to imagine him gone."

In addition to his brother, Mr. Timoney is survived by his wife, Noreen; children Sean and Christine; a sister; and two grandchildren.

Mr. Timoney will be memorialized in Florida and New York. A Funeral Mass will be said at 11 a.m. Friday, Aug. 19, at St. Patrick Catholic Church, 3716 Garden Ave., Miami Beach. Friends may call from 3 to 10 p.m. Thursday, Aug. 18, at Vior Funeral Home, 291 N.W. 37th Ave., Miami.

Visiting hours in New York will be from 2 to 9 p.m. Monday, Aug. 22, at Frank E. Campbell Funeral Home, 1076 Madison Ave. A Funeral Mass will be said at 10 a.m. Tuesday, Aug. 23, at St. Patrick's Cathedral, Fifth Avenue near 50th Street. Burial will follow at Gate of Heaven Cemetery, Hawthorne, N.Y.

215-854-2817 @cs_palmer

Staff writers Matt Gelb, Allison Steele, and Joseph A. Gambardello contributed to this article.