The good news came Wednesday night that the two had been found safe.
Mexican authorities stopped Guler at a checkpoint just across the border from Lukeville, Arizona. That's about 300 miles from San Diego. Police say 2-week-old Henry is safe and appears to be unharmed.
According to police, Guler disappeared with the baby Tuesday afternoon and threatened to harm himself and the baby if the mother told police.
When she did report it to police, they issued an AMBER Alert. The search Wednesday centered on San Diego where there were sightings of his SUV as well as a cellphone ping in a suburb there.
"They had stopped him at a checkpoint within Mexico and again, based on interview with him, they called the U.S. Border Patrol at Lukeville, gave them the name, the U.S. Border Patrol ran his name in the computer system and discovered that there was a warrant for his arrest for the child abduction," said Captain Dave Pitts with the Sunnyvale Department of Public Safety.
Now the big question is how American Border Patrol officers missed him, what with the AMBER Alert and all the media exposure on this story. In fact, border patrol agents in Lukeville had to check their computer to find out that there was a $1 million warrant for his arrest.
They are serious questions that will have to be addressed in the coming days.
With her 5-year-old daughter at her side, Henry's mother, Patricia Romero, spoke to reporters about how relieved she was her baby was found safe. She thanked the police and people who helped find her son.
Neither Romero nor Sunnyvale authorities know for sure when Henry will be returned to his mother.
Roommates describe couple's volatile relationship
We spoke with a couple of friends and former roommates with the mother. They say that she and the father of the baby had a volatile, contentious relationship. Adding that there were many arguments and many threats made by him. The final straw may have been made when she refused to move to New York with him.
We spoke with Andrew Edene, former roommate of the kidnapped baby's mother, "They had problems before," he said. "I mean, it was ongoing. And once she had the baby, she never did nothing."
"She's just crying and crying because she doesn't know where is he," adds Stephanie Ortiz, former roommate of the kidnapped baby's mother.
Ortiz and Edene roomed with the mother of two-week-old Henry Guler-Romero until recently, here at an apartment on Helen Street.
She told us that at about 4:30 p.m. Tuesday, the baby's father went to get his paycheck at a Palo Alto hotel where he works as a barista. He took the baby with him. Then Ortiz says he phoned the mother.
"He called her to say, 'I'm sorry,' and that's it," Ortiz said.
Guler disappeared with the baby. Police say he later sent her a text.
"He indicated to her that if the police were involved he would cause harm to himself and the child," said Captain Dave Pitts with the Sunnyvale Public Safety Department.
Police issued an AMBER Alert Tuesday night after the mother reported the baby missing.
Her former roommates say the couple argued often and that Guler constantly threatened her.
"Basically, 'I'll take the baby and leave and I don't need you no more,'" Edene said. "Basically stuff like that."
"And when the baby was born, 'I'm going to take him and leave,'" Ortiz added.
Police believed Guler had driven south and could be in San Diego, where he apparently has relatives.
Someone reported seeing Guler's SUV in the hillcrest neighborhood between 9 p.m. and 10 p.m. Tuesday night.
Around midnight, police picked up a ping from his cellphone seven miles away in Kearny Mesa, then another possible sighting at 3:30 a.m. Wednesday in National City.