The Lion Air plane that crashed into the ocean last week had been experiencing a "technical problem" with its airspeed indicator, and the gauge had malfunctioned on the jet's final four flights, investigators said Monday.

That included three flights that landed safely, as well as the deadly crash on Oct. 29, when Flight JT610 crashed minutes after takeoff from Jakarta, Indonesia, with 189 people on board.

The finding was announced shortly after an emotional news conference in which victims' relatives confronted government officials and Lion Air's co-founder, calling for accountability.

Lion Air reportedly knew that the plane — a brand-new Boeing 737 Max 8, which the low-cost carrier had been using for only a few months — had malfunctioned on its second-to-last flight. That flight on Oct. 28 was just hours before the fatal flight the next morning.

On Oct. 31, a Lion Air spokesman told Bloomberg that pilots had reported an issue calculating airspeed during that Oct. 28 flight. The spokesman said the instruments were examined by a maintenance crew between the penultimate and final flights. Reuters spoke to a pilot and an airport authority official who confirmed that a problem with the plane had been indicated in a radio alert.

Tracking company FlightRadar24 checked the records for that flight — JT43, which landed safely in Jakarta — and found irregularities in speed and elevation in the first 11 minutes in the air.

Now, based on the flight data recorder, investigators were able to identify two earlier flights that experienced the same problem — in every case tied to the airspeed indicator.

"National Transportation Safety Committee chairman Soerjanto Tjahjono said the problem was similar on each of the four flights," The Associated Press reports:

"Investigator Nurcahyo Utomo said investigators need to review maintenance records, including what problems were reported, what repairs were done including whether components were replaced, and how the repairs were tested before the 2-month-old plane was declared airworthy.

" 'Currently we are looking for the cause of [the] problem,' he said. 'Whether the trouble came from its indicator, its measuring device or sensor, or a problem with its computer. This is what we do not know yet and we will find it out,' he said."

Malfunctioning airspeed indicators have factored in several high-profile crashes, including two more than 20 years ago involving Boeing 757s.

In 1996, an Aeroperu crash near Lima that killed 70 people was attributed to a maintenance error that left tape and paper covering sensors used to calculate airspeed and altitude. Earlier that same year, a Turkish-owned charter flight crashed, killing 189 people, after the pilots' airspeed indicators told them the plane was moving much faster than it really was.

Both flights crashed shortly after takeoff. Audio recorded in the cockpit of each flight showed that the pilots were confused by conflicting instrument reports.

In the case of the Lion Air flight, the "black box" that was found — which is actually bright orange — contains instrument data. The cockpit voice recorder has not been located.

Divers have been retrieving bodies for days, and search efforts continue. Lion Air said Monday that nearly 70 ships have been deployed in the search, with more than 1,000 people involved.

Well over 100 body bags have been retrieved, and each body bag could contain remains from more than one individual. But only 14 victims have been positively identified so far, Lion Air says.

As NPR previously reported, Lion Air "has a spotty safety record with a number of incidents over the years, including a crash landing at sea in April 2013 that remarkably resulted in no deaths or serious injuries. Due to the problems, the U.S. and the European Union had banned it from operating in their airspace, but both lifted that restriction in 2016."

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