The columns of the four-story building apparently lacked steel support rods and sufficient concrete, leaving the dormitory in ruins and crushing children as they slept.
"Murderers!" said Gazal Gunalan, the mother of a missing 15-year-old boy. "Look at this building; it is the poor construction that took the lives of our children."
Dozens of parents waited outside the collapsed building in the town of Celtiksuyu for news of about 20 children still reported missing and who may be buried in the rubble.
The pre-dawn, magnitude-6.4 earthquake on Thursday killed at least 149 people and injured about 1,000 more. So far, 65 children have been found dead at the school.
On Saturday, relief workers used cranes and bulldozers to remove debris after trained dogs and electronic listening equipment failed to detect any signs of life. Each time another body was found, frantic parents rushed through a police barricade to check the child's identity.
Construction codes for the school required that no stones in the concrete building be larger than a pebble to ensure strength, but large stones were found on the site, said Kemal Turkaslan, head of the Ankara-branch of the construction engineers association.
"I see big stones brought in from a riverbed," Turkaslan said. "That is unacceptable."
Public Works and Housing Minister Zeki Ergezen said authorities are investigating the contractor, Seref Bozkus, who was reportedly banned in 2002 for a year from bidding for public projects because of financial irregularities.
On Friday, violent clashes erupted in Bingol (search) between police and Kurds (search) protesting a shortage of tents, food and water. Police fired shots in the air as the protesters demanding the resignation of the regional governor. Several demonstrators were injured by a police van speeding through the crowd. At least five policemen were also injured.
In villages across the area, Friday was a day of mourning. In the particularly hard-hit village of Kardeslerkoyu, villagers began burying 12 children who had lived at the boarding school in Celtiksuyu.
Turkey has suffered several massive quakes over the past decade, including one in 1999 that resulted in more than 18,000 deaths. Shoddy construction was blamed for many of the deaths, but experts say little has been done to improve building safety.
People blame contractors for stealing portions of building materials from construction projects and accused the government of inadequate inspections.
"Public buildings are collapsing just like a deck of cards," said Nihat Ozdemir head of the Turkish Contractors' Union.
Despite government promises of a crackdown, only a handful contractors were brought to justice after the 1999 quakes.
"There is no serious prosecution," Turkaslan said. "The government must do something about it immediately. We talk about the same thing after each quake."
Experts have warned the government since 1999 to demolish some 40,000 Istanbul buildings that are in danger of collapse. Many others need to be reinforced.
In Celtiksuyu, rescue crews were still picking through the crumbled concrete and twisted pipes of the former dormitory.
"This is not a school building, it is a coffin," said Alaattin Dincer, head of the Education Union.