The Orlando police department has closed its investigation into the former owners of the Pulse nightclub without filing any charges. Victims’ families and survivors of the mass shooting that killed 49 patrons at the LGBTQ+ club had asked law enforcement to investigate them for criminal culpability.

No charges will be filed against the former owners, Barbara and Rosario Poma, because probable cause did not exist for involuntary manslaughter by culpable negligence, the Orlando police said this week in an emailed statement.

About two dozen people, mostly survivors and family members of those who died in the 2016 shooting, gave statements to investigators. They said that building plans were not available to first responders during the three hours club-goers were held hostage in the club and that unpermitted renovations and building modifications had occurred.

They also maintained that the club was probably above capacity, that it had operated for years in violation of its conditional use permit, and that there were security and risk-management failures.

Despite efforts to reach the Pomas, investigators were unable to interview them. Sara Brady, a spokesperson for the Pomas, said Wednesday that they were not issuing a statement.

Investigators concluded that the lack of building plans did not hamper rescuers, that it was impossible to identify how many people were in the club that night, that the city of Orlando never took any action against Pulse when the nightclub changed its interior and that there were too many unknowns about how the gunman, Omar Mateen, entered.

None of the Pomas’ actions were done “with a reckless disregard for human life”, and “they could not have reasonably foreseen or anticipated a terrorist incident taking place at Pulse”, investigators wrote in a report.

Mateen opened fire during a Latin night celebration on 12 June 2016, leaving 49 dead and 53 wounded. At the time, it was the worst mass shooting in modern US history. Mateen, who had pledged allegiance to the Islamic State group, was killed after a three-hour standoff with police.

The Pulse shooting’s death toll was surpassed the following year when 58 people were killed and more than 850 injured among a crowd of 22,000 at a country music festival in Las Vegas. The city of Orlando purchased the Pulse property last year for $2m.