Further information about Darby’s arrest was not immediately available.
On Monday night, Pittsburgh police and detectives swarmed a sewer drain just down the block from Sheykhet's home in Oakland.
"They were looking for evidence of some sort inside of the sewer," said Peyton Miller, a Pitt student who lives nearby. "They had some contraption and they asked if they could borrow power."
Another neighbor said police have been a constant presence recently.
"There have been detectives around the house all day, the past couple of days," said John Boyer, also a Pitt student.
Miller knows Darby and Sheykhet.
"It was really shocking as the stories developed," he said. "This is the kid we met. This is the girl we met. It's tough.
"Seems like the worst stuff happens to good human beings."
The complaint says Darby was at Duquesne University after 3 a.m. on Sunday, where he asked an employee at the Union if he could borrow a phone charger. At 4:21 a.m., Darby was picked up by a car service at Brottier Hall.
Darby instructed the driver to take him to Cable Place, near the home Sheykhet shared with roommates, police said.
Between 4 and 5 a.m. that morning, five phone calls were made from his phone to Sheykhet’s, police said. She did not answer any of them.
The driver took Darby to Semple and Ward streets, where Darby asked him to wait for 10 minutes before walking in the direction of Sheykhet’s home, police said. Darby returned 10 minutes later, asked the driver to wait another 10 minutes then walked back toward Sheykhet's home.
Five minutes later, he called the driver and, in a whispered voice, asked him to wait another 10 minutes. The driver said he could not, and left, police said.
Surveillance video shows a man who looks like Darby walking in the area, stopping at Semple Street and Urie Way, and dropping a shiny object in a sewer grate, police said. He then stops further down Urie and drops an object in a Dumpster before walking down Semple toward Bates Street.
Police recovered a hammer and two knives from the sewer grate at Semple and Urie, according to the complaint. They are consistent with Sheykhet’s injuries. The Allegheny County Medical Examiner's Office said Sheykhet died as a result of sharp/blunt force trauma.
Her phone was missing from her room when she was found, police said. The last time it pinged a service tower was about 9:40 a.m. Sunday, about an hour after Sheykhet was found dead, in Irwin near the intersection of Interstate 76 and Route 30.
The complaint says witnesses, whose identities were withheld for their safety, saw Darby in that area around that time.
Darby is charged with homicide, burglary, flight to avoid apprehension, theft and possessing an instrument of crime.