Texas Department of Criminal Justice officials also said officers have seized at least one subscriber identity module, or SIM card, a postage-stamp-size tool that plugs into cell phones and transfers information from one phone to another.
A phone and a charger were found in the ceiling of a shower area in the death row building at the Polunsky Unit outside Livingston, agency spokeswoman Michelle Lyons said.
The 111 prisons in the nation's second-largest corrections system have been locked down since Monday evening after Gov. Rick Perry ordered agency officials to ferret out any contraband.
The order followed the disclosure that death row inmate Richard Tabler had made threatening calls to a state senator and had shared his illegal cell phone with at least nine of his fellow inmates.
The 10 condemned prisoners made 2,800 calls in nearly a month and the inmate's mother, Lorraine, was arrested Monday and jailed on suspicion of paying for phone minutes. It is illegal to give inmates prohibited items like cell phones or the minutes needed to use them.
Tabler's sister, Kristina Martinez, turned herself in to police in Killeen Wednesday after she was named in a warrant, Lyons said. Martinez and Lorraine Tabler were charged with providing a prohibited item to a corrections facility, a felony. Martinez's bond was set at $10,000.
The systemwide lockdown means inmates are confined to their cells and normal visits with relatives have been suspended. Employees and visitors also are subjected to searches with hand-held metal detectors.
Lyons said it could take three weeks to complete the search of large prisons, some of which -- including Polunsky where death-row inmates are house -- have more than 2,000 inmates.
Even before the lockdown, Polunsky Unit officers conducting searches after Tabler was busted with his phone found two other cell phones in the prison, officials said.
And investigators had closed or were working on 19 cases of prohibited phones or phone components on death row and some 700 cases systemwide this year alone before the Tabler case broke.
Some prisons, like the Polunsky Unit, have airport-style metal detectors. Others, like the Huntsville Unit, do not. On Tuesday, a new station with an officer equipped with a hand-held device was at the inside front door to the Huntsville Unit.
At a hastily called meeting Tuesday in Austin of the criminal justice committee he chairs, Sen. John Whitmire, D-Houston, who Tabler called, grilled state prison administrators for what he called rampant security failures and a lax attitude.
John Moriarty, the department's inspector general, blamed a handful of corrupt officers for smuggling phones.
A phone can command a bribe of $2,000 -- nearly a month's salary for a rookie corrections officer -- and be used to coordinate with gangs on the outside. The same system is used to smuggle in drugs and cigarettes, he said.
"All it takes is one (bad officer) and you've got a big problem," Moriarty said.
Tabler, from Killeen, was convicted last year of fatally shooting Mohamed-Amine Rahmouni, 25, and Haitham Zayed, 28. He also confessed to killing Tiffany Dotson, 18, and Amber Benefield, 16. All four had ties to a Killeen strip club. He recently told his trial judge he wanted appeals waived so he could be put to death.
Individual lockdowns at prisons are fairly routine but the overall lockdown is believed to be the first since March 2000, after an inmate used dental floss or a similar coated string to cut his way out of his cell, then attack and kill a rival gang member who was being escorted by officers to a shower.
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