Six months after a botched drug raid left a south Houston couple dead and sparked a police scandal, a private investigation has raised new and troubling questions about the official narrative of the case.

The forensics expert hired by relatives of the couple killed in the failed bust found that police apparently fired some of the fatal shots through a wall, while standing outside the Pecan Park home.

The independent review, released in a court filing Thursday, also highlighted the perplexing presence of two bullet holes in an inner room of the home, shot into the wall from inches away but more than four yards from the shootout by the front door.

Taken in conjunction with video footage that appears to have captured the sound of two shots half an hour after the gunbattle, family attorney Mike Doyle argued in a 22-page legal petition that the independent findings raise enough questions to merit further investigation in preparation for a lawsuit.

In Thursday's court filing, he asked a local state district judge for permission to question police officials under oath about the raid and about "abuses" throughout the narcotics division.

"Given the indications that the City's story does not line up with the physical facts at the Harding Street Home," Doyle wrote, "the Nicholas Family believes the Court has more than sufficient basis to order the depositions requested to investigate the wrongful death, civil rights, and other claims arising from the Harding Street Incident."

At a news conference Thursday at the Buffalo Soldiers National Museum in Midtown, Charles Bourque — who is also representing the Nicholas family — described the court filing as a "drive for the truth."

"We want to find out what's happened," he said. "We've tried every other method, through public records requests and otherwise. The information hasn't been given. That's why we filed the pleading we filed today, so we can begin conducting a formal discovery process. So we can discover the truth."

Nicole DeBorde, the attorney representing former narcotics officer Gerald Goines — the case agent at the center of the raid — said the new filing didn't raise any red flags or new questions.

"This is a very one-sided, hired-expert-based spin filed with the end goal of getting a big payout from the city and its taxpayers," she said. "Law enforcement, both federal and state, is not going to release reports in the middle of an investigation — in part so that civil lawyers looking for a big payout cannot manipulate the data."

Houston Police Officers' Union Vice President Doug Griffith also scoffed at the idea that law enforcement would turn over evidence in the middle of a criminal probe.

"I will trust the police investigation before I trust someone paid by a potentially biased client," he said.

Chief Art Acevedo declined to comment Thursday evening.

Harris County District Attorney Kim Ogg, meanwhile, cautioned against jumping to conclusions.

"We will get to the truth," Ogg said. "And while we welcome any information about the incident that unfolded on Harding Street, we caution everyone to wait for all the evidence to be brought forth before making a decision about what happened that day and who is responsible."

On HoustonChronicle.com: Federal grand jury hears testimony from Houston police officers about botched Pecan Park raid

The deadly raid started on the evening of Jan. 28, after Squad 15 narcotics officers burst in the front door of the Pecan Park home of Navy veteran Dennis Tuttle and his wife Rhogena Nicholas. According to the Houston Police Department, officers opened fire as soon as a pit bull lunged at them — though the outside forensics review showed the dog was shot and killed at the edge of the dining room, 15 feet from the front door.

At the sound of the gunshot, police said, Tuttle came running out from a back room and allegedly opened fire with a .357 revolver, striking the first officer through the door.

The wounded lawman fell on the couch near Nicholas, who allegedly made a move for his weapon. A back-up officer opened fire and killed the 58-year-old, according to the police version of events.

The gunbattle continued and, in the end, Tuttle and Nicholas were killed and five officers injured, four of whom were shot. Authorities still haven't clarified who killed whom, but police maintain the officers were not hit by friendly fire.

Though the no-knock raid was intended to target heroin dealers, police turned up only small amounts of cocaine and marijuana. Goines later retired under investigation amid accusations that he'd lied on the search warrant used to justify the raid. His partner Steven Bryant followed suit in mid-March, retiring under investigation as well.

Meanwhile, prosecutors undertook a review of all the cases the pair handled, tossing more than two dozen pending charges. Houston police conducted an internal investigation and in recent weeks — under threat of subpoena — turned over information about the squad's confidential informants to the Harris County District Attorney's Office for an ongoing investigation there.

Authorities have repeatedly hinted at the likelihood of criminal indictments for those involved, and on Wednesday two Houston police officers testified in front of a federal grand jury.

On HoustonChronicle.com: DA threatens to subpoena police for names of informants behind deadly Harding Street drug raid

As the police investigation unfolded, Nicholas'relatives launched their own probe, spurred in part by the police department's failure to retract initial condemnations of the slain couple as drug dealers.

The department's silence on that issue still rankles, Bourque said.

"From the beginning, it's been an attack on her character, and telling these things she supposedly did," he said. "That the mother knew, and her brother knew, was not something Rhogena would do."

That same month, the slain couple's relatives got their hands on video of the raid and started more closely questioning the official timeline. Particularly troubling to the families and their lawyers were the two lone gunshots about 30 minutes after the raid ended.

Minutes after those final shots, police on the scene repeatedly said, "Both suspects down."

To Doyle, that didn't square with the official narrative about a gunbattle that ended "almost as soon as it started," according to the new court filing.

"There is no explanation at this point for that," he said Thursday.

Questions about those shots — combined with the city's refusal to release audio from the 911 call — also spurred the decision to hire an independent expert to review the case. An outside team led by former senior agent and forensic consultant for the U.S. Naval Criminal Investigative Service Mike Maloney spent four days in May combing through the trashed home and searching for any unexamined evidence.

"When the scene was finally fully analyzed, it did not appear that HPD conducted a full ballistic recovery to even test the City's story," Doyle wrote in Thursday's filing. "Instead, HPD's investigation at the Harding Street Home left what appeared to be significant forensic materials untouched and unrecovered."

The new forensics team found no signs the pair fired shots at police, but instead came across empty drug baggies, bullets, a shirt tagged as evidence, and two teeth — likely Tuttle's — sitting in a splotch of dried blood.

"It doesn't appear that they took the basic steps to confirm and collect the physical evidence to know whether police were telling the truth," Doyle told the Chronicle at the time. "That's the whole point of forensic scene documentation. That's the basic check on people just making stuff up."

After that review, Maloney's team offered some initial findings at the scene, but it wasn't until Thursday's filing that they released the two new key claims.

Over the course of six pages filled with pictures, diagrams and an analysis of bullet trajectories, the court papers lay out evidence about where the person who shot Nicholas was standing at the time.

On Thursday, Doyle said his investigator's findings strongly disputed the narrative provided by the Houston Police Department in the days and weeks after the raid.

Doyle said his team had recovered the bullet that killed Nicholas, and that evidence showed she was shot by an officer standing outside of the house, who fired through a wall — meaning he would not have been able to see her — striking her as she turned away from the door, toward where her dead dog was found.

Rhogena's brother, John Nicholas, said he was still waiting for closure.

"It's a shame you're sitting in your house, minding your own business and somebody shoots you," he said.

"All I want is the truth, some kind of closure," he said. "I hope this doesn't happen again, and hope the court will allow us to move forward in this investigation."

Breaking News: Get email alerts from Chron.com sent directly to your inbox

The filing also describes the presence of two holes in the back wall of the dining room, from weapons fired at close range. According to police, the shootout took place in the living room, where Tuttle fired toward the incoming officers before he and his wife were shot.

"An unidentified person held a weapon against the inner dining room wall and fired 2 shots into the inner dining room wall towards the kitchen (or within 2-3 inches of the inner dining room wall)," the filing notes, "as confirmed by lab testing of swab samples."

The findings laid out in the court documents are based on the information still available to Maloney and his team after police came through and did their review, removing some evidence, including shell casings and bullets. To do a full investigation and make firmer conclusions, the outside team would need to know the locations and types of bullets and spent casings previously recovered, review documentation of the wounds on police, get a full accounting of the weapons used, and then find out the number of unused bullets.

So far, they haven't been able to do that.

In DeBorde's view, there is nothing unusual about authorities being tight-lipped in the course of an ongoing investigation.

"Law enforcement's investigation needs to be independent," she said. "When they are done, they will release it."

But Doyle is hoping the slew of unanswered questions and new forensic findings is enough to prompt the judge to grant him permission to depose city and police officials.

The filing asks for depositions from Commander Paul Q. Follis and Lt. Marsha Todd — two Houston police supervisors who oversaw Goines in the narcotics division — to shed light on the department's policy and practice around no-knock warrant, the "abuse" of the confidential informant program, and the monitoring of guns, drugs and money used by the narcotics division.