The L.A. County Registrar’s Office is investigating how a countywide parcel tax measure meant to bolster firefighting services was initially left off of 66,000 mail-in ballots in two cities.

Measure FD was intended to be on the ballot in fire districts where the L.A. County Fire Department provides the main service. It asked voters to consider a levy of 6 cents per square foot on property improvements, with a goal of bringing in $134 million each year to emergency services.

With about two-thirds of the ballots counted Friday, it was clear that voters liked the measure, but not enough. FD was falling well short of the two-thirds majority it required for victory, according to the Los Angeles County Registrar-Recorder/County Clerk’s office.

But that didn’t quell scrutiny of the issue, which appeared amid a wider inquiry into series of major breakdowns, including three-hour-long waits to vote; inoperable voting machines, insufficient and/or ill-trained staff and connectivity issues.

They led to bottlenecks, and in some cases, turning voters away from the polls in a brand new $300 million system that had county leaders “losing confidence,” and frustrated residents chastising pollworkers.

As part of a report due back within 45 days, investigators will probe those breakdowns and others. They’ll also assess the Measure FD mystery.

The measure was initially left off ballots in Hawthorne and Pomona, and was included on ballots in areas where voters weren’t eligible to weigh in, including Lynwood and Palos Verdes Estates. Only voters who lives in areas serviced by the LA Fire Department were eligible.

In promoting the measure, Los Angeles County Fire Chief Daryl Osby said the income was necessary for his department to upgrade engines and equipment, especially as the fight against wildfires appears to be increasing. The department also is battling to keep up with substantial increases in calls for service.

The measure was important, Osby said, because it’s the only way the department could increase its budget. Unlike other county departments that can request increased allocations from the Board of Supervisors through the general fund, the Fire Department is funded from parcel taxes and fees paid by residents and businesses in the areas it serves.

A fiery Board of Supervisors sounded off on the issue last week as they faced top L.A. County election official Dean Logan, the county’s registrar-recorded.

“This was a measure that we voted unanimously on for our fire department to put before the voters, and for you to leave that off of 66,000 ballots, then sending them another ballot and asking them to mail two back in?” asked Supervisor Janice Hahn. “You’re gonna have to study that. I want to know, of that 66,000 people, did they all mail two ballots back in?”

Mike Sanchez, a spokesman for the registrar’s office, said officials were “proactive” from the start, on Feb. 4, when they realized that Hawthorne and Pomona voters did not get the measure on their vote-by-mail ballots.

“We notified those voters with a letter and — a supplemental ballot — that the measure wasn’t included initially with the vote-by-mail ballot, and gave instructions on how they could fill it out and return those ballots together or separate,” he said. “We also email-blasted those impacted voters, sent automated robocalls to the those voters.”

Social media and signs at voting centers in those cities were also posted, letting voters know. Also, a press release was sent out on Feb. 6.

“We regret the omission,” Logan said. “We identified the error and are acting quickly to ensure affected voters receive materials with sufficient time to mark and return both the original and supplemental ballots.”

The measure was included on ballots that were cast on voting machines, which were programmed to include all contests and measures, including Measure FD, for all Pomona and Hawthorne voters.

Officals said that even if 100% of the impacted voters voted on the measure (either Yes or No) the outcome would not be different, because the measure required two-thirds of voters to pass. As of Friday, yes votes led 339,923 (52.36%) to 309,294 (47.64%).

But the registrar’s office was still counting ballots in the delayed tally — a process that has until March 27 to be certified.

Officials acknowledged that ineligible voters in the cities of Lynwood and Palos Verdes Estates errantly received vote-by-mail ballots that contained Measure FD. When those voters returned their vote-by-mail ballots the registrar’s office flagged their return to “re-make those ballots without the measure on it,” officials said.

The county is compelled by law to make sure all registered residents who vote have their ballot counted — which is why, officials said, measures were taken to supplant the errant ballots with new ones, adding Measure FD.

At the moment, there’s no “do-over” in the works to enable voters who didn’t vote on the measure to get a second chance.

That said, county fire officials seemed satisfied with the early “corrective actions.”

“Certainly it was concerning when we found out,” said Deputy Chief Jon O’Brien. “But I believe the Registrar’s office offered up a pretty robust action plan to mitigate its exclusion in those cities.”

O’Brien was department leader in charge of voter outreach, empowered to sell voters on how badly the firefighters needed the new gear. He said he as satisfied with the steps officials took to try to correct the problem. But he also was eager to see the outside firm’s analysis of the situation.

“It seemed to be appropriate for the situation,” he said of the registar’s fixes. “The registrar’s office was up front about the omissions. We had every reason to believe it would ultimately be successful. But we shall see.”

Senior Editor Tom Bray contributed to this report.