The young man charged in the Santa Fe High School shooting rampage that left eight students and two teachers dead purchased more than 100 rounds of ammunition before the shooting on a website that never verified his age, attorneys alleged in an amended civil lawsuit filed Thursday.

The filing alleges that on March 2, 2018, Dimitrios Pagourtzis, then a 17-year old junior at Santa Fe High School, ordered 50 rounds of hollow-point handgun ammunition and 105 rounds of 12-gauge shotgun ammunition from the website Luckygunner.com. Two weeks later, he purchased 35 additional rounds of shotgun ammunition from the same website, according to the suit.

“We’ve identified another actor in the chain of events that led to this horrific, tragic shooting,” said Eric Tirschwell, managing director of Everytown Law, part of the legal team that filed the petition. He said the lawsuit claims the website “broke federal law and didn’t verify the age of the purchaser, and we see what the result was.”

Tirschwell and Everytown Law, the legal arm for Everytown for Gun Safety Support Fund, a nationwide group, filed the petition on behalf Abdul Aziz Sheikh and Farah Naz, the parents of Sabika Sheikh. A Pakistani exchange student who spent a year at Santa Fe High School, the 17-year-old was one of the eight students killed during the school massacre.

The complaint alleges Pagourtzis was not required to submit proof of his age to make the purchase, create a Luckygunner account or set up a secure two-step authorization. He checked a terms-and-conditions box agreeing that he was not under 21, and used prepaid American Express gift cards to pay for the ammunition.

Pagourtzis would use the ammunition in the May 2018 shooting spree, the lawsuit alleges. Pagourtzis is charged with capital murder in the shooting, which police say was carried out with a shotgun and revolver owned by his parents. He admitted to being the mass shooter after his arrest, according to court documents. He faces life in prison with the possibility of parole after 40 years if convicted. He is not eligible for the death penalty because he was 17 at the time of the shooting.

The amended petition is part of a civil lawsuit filed against the suspect’s parents, Antonios Pagourtzis and Rose Marie Kosmetatos, alleging that they knew their son was exhibiting extreme behavior but failed to prevent him from accessing their firearms, which authorities believe were used in the shooting.

Sheikh's parents, who live in Karachi, Pakistan, joined the lawsuit in November 2018 and have been vocal in decrying gun violence ever since. In a statement, Abdul Aziz Sheikh and Farah Naz said they are committed to fighting for accountability and for a safer future.

“People need to know just how easy it was for the shooter to buy ammunition from a website that failed to take even basic steps to protect the public,” they said in a statement.

Ron Rodgers, the attorney representing Pagourtzis’ parents in the civil suit, said he was aware of the amended petition, but declined to comment because he said it doesn’t directly pertain to his clients.

The information about how the ammunition for the Santa Fe shooting was acquired was not previously revealed. Galveston County District Attorney Jack Roady, who is prosecuting the capital murder case, has kept a tight lid on public information connected to the shooting.

The Texas Public Information Act gives prosecutors sweeping authority to keep documents secret — including medical examiners' reports, police radio communications, incident reports and almost everything else — thanks to a law enforcement exception written into the law.

Law enforcement agencies have withheld all public documents connected to the Santa Fe shooting, which occurred some 35 miles southeast of downtown Houston, claiming it will interfere with Pagourtzis’ prosecution.

Federal law prohibits minors from purchasing handgun ammunition, and bars licensed gun companies from selling handgun ammunition to minors or selling shotgun ammunition to anyone they have reason to believe is under 21.

The new filing lists Luckygunner.com, along with its owners, Red Stag as additional defendants in the lawsuit. The suit claims Red Stag mailed the ammunition to Pagourtzis via FedEx without verifying his age or requiring an adult to sign for the package. Subpoenas have not yet been issued to either company.

Neither Luckygunner.com nor Red Stag responded to requests for comment.

Pagourtzis is being evaluated and medicated at North Texas State Hospital in Vernon, a maximum-security mental health facility. He was evaluated by three independent psychiatric experts, all of whom agreed that he was not fit to stand trial in his current mental state.

Galveston County prosecutors did not challenge the finding and state District Judge John Ellisor on Nov. 15 officially signed the order declaring Pagourtzis’ incompetent.

nick.powell@chron.com