Silverio Deniz held a toothbrush handle and a folded sock.

A box of tissues sat on a table nearby to wipe tears from his red-rimmed eyes.

"They say my son swallowed a sock and a toothbrush," he said in Spanish, holding back tears. "How is that possible?"

Others are wondering the same.

In May, Deniz's son, Jose de Jesus Deniz-Sahagun, was found dead inside his cell at the Eloy Detention Center, which is run by the Corrections Corporation of America under contract with Immigration and Customs Enforcement.

A medical examiner determined the 31-year-old immigrant from Mexico killed himself by stuffing a sock down his throat. A plastic handle was found in his stomach, possibly from a previous suicide attempt.

His death was the latest in a string of suicides at the Eloy Detention Center, which has become the deadliest immigration detention center in the nation.

Deniz-Sahagun was at least the fifth person to commit suicide at Eloy since 2003, according to an analysis of data by The Arizona Republic.

The Republic also found that none of the nearly 250 other detention centers nationwide had more than one death attributed to suicide or asphyxia since 2003.

The five deaths at Eloy "while no other center has had more than one merits concern," said Dr. Allen Keller, associate professor of medicine at New York University and director of the NYU Center for Health and Human Rights. "It raises really troubling questions about what care was provided and what evaluations were being done."

The suicides at Eloy are particularly troubling, critics say, considering that 9 percent of detention deaths nationwide since 2003 occurred at Eloy, where 14 of the 152 total deaths occurred.

Eloy is one of the largest detention centers in the nation with 1,596 beds.

Still, critics say the suicides show that the facility has problems and needs to do more to prevent deaths among detainees. They cite questions about adequate medical care, effective suicide monitoring and staffing levels as some of the issues.

"Mr. Deniz-Sahagún is just the latest in a series of fatalities at Eloy, and it is clear that something must be done about it," U.S. Rep. Raúl Grijalva, D-Ariz., said in a statement.

Grijalva has called for an independent investigation into Deniz-Sahagun's suicide.

"Eloy has had 14 detainee deaths in just 12 years — that's appalling, no matter how you look at it," Grijalva added. "ICE's policies state that they review each death, so it begs the question, what are they finding in their reviews? What are they doing to fix this problem? Clearly, not enough."

Autopsies on the 5 suicides

The Republic obtained autopsy reports for the five suicides at Eloy through public-records requests from the Pima and Pinal county medical examiners' offices.

The Republic also received autopsy reports for seven of the nine other deaths at Eloy from the Pima, Pinal and Maricopa county medical examiners' offices. The other two Eloy detainees died at the Maricopa Medical Center, but their death records were not on file at the Maricopa County Medical Examiner's Office.

Beside Deniz-Sahagun, the reports show the four detainees who committed suicide at Eloy had hanged themselves, two with bedsheets and two with shoelaces.

Juan Salazar-Gomez was the first detainee to kill himself at Eloy on Dec. 14, 2005.

According to his autopsy report from the Pinal County Medical Examiner's Office, the 29-year-old Mexican immigrant was found hanging from a green bedsheet in his single-person cell. The autopsy identified marks on his wrists and arms as consistent with self-inflicted wounds.

Jose Lopez-Gregario, 32, died Sept. 29, 2006. He was found hanging from his bunk with a bedsheet.

Lopez-Gregario had been placed on constant suicide watch that Sept. 24. But after four hours, a staff psychologist interviewed him and reduced the watch to 15-minute checks.

After his death, investigators found that a sick-call request he made went unanswered for seven days, even though he was on suicide watch, according to public records obtained by the New York Times and posted on its website.

The request "should have been responded to with some sense of urgency" an investigator wrote. "Limited efforts were being made to assist the detainee."

Two more suicides occurred within three days of each other in 2013 when two Guatemalan detainees hanged themselves. Both had been in ICE custody a little over a month.

Elsa Guadalupe-Gonzales, 24, hanged herself with shoelaces on April 28, 2013. Guadalupe-Gonzales had been taken into ICE custody after crossing the border illegally and was waiting for immigration hearings related to her removal case.

Jorge Garcia-Maldonado, 40, died two days later, also by hanging himself with shoelaces from his top bunk. He had been transferred to ICE custody after being booked at Maricopa County Jail on an assault charge.

According to ICE press releases, each received two routine medical screenings, but did not seek any medical or mental-health treatment.

ICE: Committed to safety

ICE did not respond to questions about the five suicides at Eloy.

Following Deniz-Sahagun's death, ICE issued a statement saying all detainee deaths are reviewed by the agency's Office of Professional Responsibility. The office is currently investigating his death.

"ICE is committed to ensuring the safety of all those in its custody," ICE officials said in the statement. "As such, OPR will be reviewing the Eloy facility's compliance with ICE standards and policies, including those relating to suicide prevention and intervention."

Following the two suicides in 2013, ICE vowed to have its mental-health personnel work with the facility administrator at Eloy to provide further suicide-prevention and -awareness training for detainees and facility staff.

ICE officials also said they were sending a team of specialists to review the Eloy facility's compliance with ICE standards on suicide prevention and intervention.

The agency said it would assess the Correction Corporation of America's staffing model "to ensure it provides appropriate supervision and monitoring of detainees at the facility." At the time, ICE also said CCA would conduct its own internal review of suicide-prevention policies.

Rep. Grijalva called earlier this month, in a letter to Homeland Security Secretary Jeh Johnson, for the results of ICE's 2013 review to be made public. The congressman said he has yet to receive a response.

Inadequate medical care?

According to ICE's standards for preventing detainees from committing suicide or harming themselves:

— Detainees should receive a mental-health screening within 12 hours of admission.

— Mental-health professionals should be available 24 hours a day for immediate consultation.

— Detainees at risk for self-harm or suicide shall be referred to the mental-health provider for an evaluation within 24 hours.

— Until the evaluation, the detainee shall be in a secure environment on a constant one-to-one visual supervision.

"Suicidal detainees require close supervision in a setting that minimizes opportunities for self-harm," the standards said.

Whether Eloy meets these standards is another question, critics say.

New York University's Dr. Allen Keller has found a correlation between the length of time in detention and psychological symptoms during his research.

"When you are serving time for a crime, you know what your sentence is," Keller said. "In immigration, it is often open ended. That uncertainty adds a very substantial level of stress."

Eloy needs to "look strong and hard" at its mental-health care, Keller said.

"Given that Eloy jumps to the top (of the number of suicides) on this, it behooves them to be particularly cautious and conservative," Keller said. "Provide more treatment, more care, more evaluation not simply by guards and video cameras but by clinicians."

Suicides in jails and prisons are difficult to prevent entirely, explained Alex Friedmann, associate director of the Human Rights Defense Center.

But when they happen multiple times at the same facility, it should raise concerns. "What we look for are patterns and issues that are commonalities," Friedmann said. "Prisoners asking for mental-health care and not being given it, not being monitored on suicide watch or delays in providing screenings."

For privately contracted facilities holding detainees, any money spent on medical care affects their bottom line.

"In our experience, medical care is particularly bad in privatized facilities," Friedmann said.

CCA declined to comment for this story, referring all questions to ICE.

Staffing problems in past

Eloy has had problems with medical care and staffing in the past.

ICE Health Service Corp. is primarily responsible for the medical and mental-health care to individuals in ICE custody, but responsibility is also shared by private-prison providers.

Conditions are governed by ICE's national detention standards, which are not legally binding. Standards created in 2011 require that "detainees shall be able to request health services on a daily basis and shall receive timely follow-up."

The general population at Eloy requests health services by depositing a written request in a designated box near food service, according to a 2009 audit by the American Correctional Association Standards Compliance.

"Average time from initial request to being seen is less than 24 hours," the audit said.

Jose Mejia, who was detained in Eloy for five months in 2013, said complaints about medical services were common among detainees.

"Everyone there had complaints about their medical services," Mejia said in a recent interview. "They'd tell you to drink water. That's all you need, more water, they'd tell you. That was the response from all the doctors. Drink water."

He said it took a week to see a doctor after he complained of back pain.

A 2011 report by the American Civil Liberties Union found repeated complaints about medical care and mental-health care in Arizona detention facilities.

"The majority of complaints included waiting a long time to see a doctor for chronic conditions or conditions that arose after somebody came into detention," said Victoria Lopez, an ACLU attorney and author of the study based on more than 100 interviews with detainees.

The report also noted how many detainees' medical concerns are often dismissed with the response to drink more water.

"The water here is like magic, it cures everything," Lopez said sarcastically.

Unusual suicide

Dr. Rebecca Hsu, a private forensic pathologist, looked at the suicide autopsy reports for The Republic.

"I don't like the most recent one (Deniz-Sahagun's) because people usually don't choke on something they shove down their own throat," Hsu said.

The autopsy also suggested that Deniz-Sahagun may have attempted to kill himself earlier. It found a 31/2-inch piece of white plastic in Deniz–Sahagun's stomach, which the medical examiner has said resembled a toothbrush handle.

The toxicology report showed no signs of drugs or alcohol in Deniz-Sahagun's system.

Deniz-Sahagun, a 31-year-old Mexican immigrant, entered the detention center on May 18 after he was captured trying to enter the U.S. four days earlier. On May 19, he was evaluated for "delusional thoughts and behaviors for which he had to be restrained," according to the autopsy. He was placed on constant watch because of concerns about suicidal intentions.

A day later, however, Deniz-Sahagun was taken off constant watch. He was placed in a single-person cell with video monitoring and security checks every 15 minutes. After less than 48 hours in Eloy, he killed himself.

Dr. Gregory Hess, the Pima County chief medical examiner who conducted Deniz-Sahagun's autopsy, watched video surveillance of someone checking on Deniz-Sahagun. Hess told The Republic the checks were done "about every fifteen minutes" as required.

Keller said he would want to know what happened between the decision to place Deniz-Sahagun on around-the-clock monitoring and his death.

"This individual was deemed a danger to himself. Why wasn't he put in a psychiatric hospital, which is a facility specifically trained to do this?" Keller said. "In this case, it really had fatal consequences."

Hsu criticized the 15-minute checks.

"I think we have seen in prisons across the country, 15 minutes is way too long," she said. "If somebody is under a suicide protocol, it should be well within their ability to keep them alive. I think the criticism is about having lousy current protocols."

Deniz-Sahagun's parents are demanding answers about the circumstances of their son's death.

"I think a person with high hopes and dreams isn't capable of taking their own life," his sister Rosario Deniz said after a press conference in late June. "We think that there's something they're hiding."

"We want to know the truth in this case."

Deniz-Sahagun has three children living in the United States.

"My brother had many hopes," Deniz said. "He was always looking ahead and wanted to give his children a better future. He wanted them to be well. That's why it makes no sense to say he took his own life."