Cops have arrested the menacing mugger accused of robbing a 10-year-old Brooklyn boy of $8 as he and his younger sister walked home from a local pizzeria — allowing the scared kid to breathe a sigh of relief.

“I’m glad they got him,” Alex Medina, age 10, told the Daily News at his Brooklyn home Saturday as his mother Ana Garcia stood by his side. “It makes me feel relieved that he’s caught, and he won’t do that to other kids.”

Police said they apprehended suspect Demba Ba, 24, in the area on Friday morning. He’s accused of grabbing cash from Alex and his 7-year-old sister on Sterling Place near Utica Ave. in Crown Heights around 11 a.m. on June 7.

Ba, who is on probation for a previous robbery, is homeless and was staying at a Crown Heights shelter about a mile from the scene of the robbery, NYPD Chief of Detectives Joseph Kenny said at a briefing on Tuesday.

Alex had been going back and forth to the Crown Fried Chicken and Pizza around the corner from his home to pick up food for his family that Friday morning when the thief spied him.

“He asked me if I can give him $5, but I ignored him and walked away,” Alex told the Daily News. “The second time I went to the pizzeria, he came, grabbed my hand and took the money and just ran off.”

Neither Alex nor his younger sister who was with him was physically harmed.

Surveillance video seen by the Daily News shows Alex holding the money in his left hand as he carried a black plastic bag around his wrist. As the robber catches up, Alex and his sister turn around and stop.

The mugger moves in, wrenching the cash out of Alex’s hand as the boy tries to pull away, the video shows. The youngster then takes out a phone as the robber walks away.

Alex called his mother, who called the child’s father. A short time later Alex and his dad drove around the area and spotted the suspect. Dad took a photo of him moments before he ran off.

The photo led to a Crime Stoppers tip, which helped police identify Ba as the suspect.

Cops charged Ba with third degree robbery, grand larceny, petit larceny, criminal possession of stolen property, harassment and acting in a manner injurious to a child. His arraignment in Brooklyn Criminal Court was pending Saturday.

“We’re feeling good now, even better now,” Alex said when he was told about Ba’s arrest. “I was sad when it happened, but I’m just glad I didn’t get hurt.

“I don’t want him to hurt anyone else,” he said.

A week after Alex’s robbery, cops were investigating a second disturbing crime against a child, this time in Queens.

Police on Saturday were hunting for a tattooed man armed with a machete who sexually assaulted a 13-year-old girl in Kissena Park on Friday morning, while the helpless child was tied to a classmate. The suspect, who was sporting braces and had a tattoo of a horned boar on his chest, robbed the two children of their cellphones as he made his getaway, cops said.

Anyone with information regarding the Queens attack is urged to call NYPD Crime Stoppers at (800) 577-TIPS. All calls will be kept confidential.