In 2013, Williams was paid $108,025 in overtime on top of his annual salary of $86,762, along with stress pay and shift differentials, according to city records. That's a total of $211,444.
The overtime makes Williams the third-highest-paid city employee, behind only Police Commissioner Charles H. Ramsey ($271,856) and Medical Examiner Sam Gulino ($247,619).
Nutter's official salary is $210,806, but he is paid $176,155 because he has forgone cost-of-living raises since 2008, when he took a self-imposed 10 percent pay cut as a nod to the city's struggling finances.
Williams did not return phone calls Tuesday.
His overtime earnings stand out in a year when Philadelphia recorded its fewest homicides since 1967.
In 2013, Williams made about $26,000 more in overtime than any other police supervisor - and $2,146 more than his busiest detective, who would likely be buried in court notices and busy with street work.
He made $18,369 more in 2013 than he had the previous year, when he was in a different homicide squad at a time when the city recorded 84 more killings.
Even in years when Williams was not in charge of the busy overnight shift, he often made more in overtime than other police supervisors. Five times since 2007, he has been paid more overtime than any other police supervisor. In those seven years, he was paid $577,159 in overtime, city records show.
His earnings in 2013 - signed off on by his commanding officer - have gotten the brass' attention, Ramsey said Tuesday.
"We are looking into it to make sure that all that overtime was necessary," he said. "It's not court time, and we are not concerned with overtime in general unless there are abuses or people working unnecessarily. I'm not saying that is what he did, but we need to take a look.
"We are working with his commanding officer to make sure that he monitors it."
Ramsey said Williams is a "good lieutenant and works an active squad."
Perhaps, Ramsey said, a review would show the unit needed more manpower.
"If I am short and they need another lieutenant, then I will find one," he said.
John McNesby, president of the Philadelphia police union, said Williams should not be punished because so many homicides happened on his watch.
"Mel Williams doesn't schedule homicides," McNesby said. "He's got to stay till the last one of his detectives leaves. . . . He's not at home, he's working there all the time doing his job and doing something for the city.
"He should be given a medal," McNesby said.
As commissioner, Ramsey has significantly decreased overtime. He created an overtime management office and scrutinized court-related costs, slashing annual overtime from $76 million in 2008 to $58 million in 2011.
The department's overtime totals include payments to officers working private security jobs during off hours - at banks or stadiums, for example - that is eventually repaid to the city by the private companies.
Last year, the department's overtime costs rose to about $66 million, which Ramsey attributed mostly to a departmentwide 3 percent pay increase and manpower shortages.
" Overtime is not a bad word," Ramsey said. "We just have to make sure people are earning overtime for a reason, and not just to earn overtime."
Williams was one of only three city employees to break the $200,000 salary mark because of overtime earnings.
Two paramedics, Lawrence Amaker - who regularly places near the top of annual city overtime lists - and Roy Burkett Jr. - a 29-year veteran of the Fire Department - earned more than $200,000 including their overtime income, according to city records.
The Fire Department's overtime budget in 2013 was $37 million, up from $19 million in 2009.
Mark McDonald, a spokesman for Nutter, said the department had 273 vacancies, but would soon welcome a class of 170 firefighters. Thirty-five paramedic candidates will soon enter the academy in the hope of filling other vacancies, he said.
An Inquirer analysis of city payroll records from the last seven years shows that after a decrease in overtime payments in 2009, total citywide overtime costs have risen steadily, along with the number of city employees.
Filling out the rest of the city's top overtime earners in 2013 were homicide detectives who work the grueling overnight shift. Three of the detectives from the unit earned more than $100,000 in overtime, city records show.
While Williams' overtime drew attention since he is a supervisor and not eligible for court pay, Ramsey said he had no problems with the line detectives' earnings.
"Our homicide investigators are getting results," he said, saying the city's homicide clearance rate was 70.5 percent last year, up from about 60 percent in 2011.