A District man has been charged with first-degree murder in the death of his 5-week-old son after he squeezed the infant tightly to quiet him and fractured his vertebrae in the process, authorities said.

Robert Smith Sr. of the 3700 block of Ninth Street NW was arrested Monday and ordered to remain in the D.C. jail until trial. Magistrate Judge Renee Raymond said she found “substantial probability” that Smith was a danger.

According to D.C. Superior Court documents, Smith told a D.C. homicide detective, Jedd Worrell, in an interview at his home on the evening of his son’s death that his son, Robert Jr., woke about 7:30 a.m. on Aug. 4, crying. The infant’s mother told detectives that Smith offered to check on the boy and that she went back to sleep.

Smith, 28, told Worrell and other detectives he “grabbed” the baby and squeezed him tightly around the torso, something he had previously done whenever the infant would cry or become fussy, according to the documents. At one point, he told detectives, he heard a cracking sound. He then fed the baby his formula and placed him back in his sleeper.

Then, Smith went back to sleep, he said.

When the baby began crying again about 9:30 a.m., Smith said he asked his girlfriend to check on him. She told detectives that she sat with the infant for about two hours and tried to feed him but that he did not finish his bottle. At the time, she said she thought Smith had fed the baby earlier. She placed the infant in his sleeper and went back to sleep. Later that day, she checked on the baby and noticed that he was not breathing.

According to the court documents, the infant’s mother screamed for help and Smith began CPR on the baby.

The medical examiner later found rib fractures, both recent and old; a fractured vertebra; a fractured wrist; and a scabbed abrasion on the back of the infant’s head.

Smith told the detectives that it was often “difficult” when he was alone with baby. According to the court records, he said he squeezed the infant about three or four times in the days prior to his son’s death. He also said that at one point, while bending over to pick up a diaper, he had forced the infant to bend backwards, causing the child to go limp in his arms. Smith also described himself as a “monster.”

At Smith’s initial hearing on Tuesday, Natalie Lawson with the Public Defender Service argued that he should be released from jail because he had no prior arrests, had a job and holds a bachelor of science degree from the University of the District of Columbia.

“Mr. Smith’s conduct was not intentional. He was a good dad in the short time his son was here,” Lawson said.

But Assistant U.S. Attorney Glenn Kirschner argued that Smith should remain in jail. “This was not a momentary lapse of judgment. This was repeated conduct over the course of this child’s life.”

Smith’s next hearing is scheduled for Aug. 27.