A registered sex offender suspected in a spree of South Bay robberies and kidnap attempts -- including the failed abduction of a teenage girl who fought back after feeling a knife put to her neck -- was in custody Thursday, police said.Leonard Earl Scroggins, 32, was arrested Wednesday night at Kimball Park in National City following a short road and foot chase, according to police.About 9 p.m. Tuesday, Scroggins allegedly confronted a 17-year-old girl in the 500 block of Oxford Street in Chula Vista and demanded money, Chula Vista Police Department Capt. Gary Wedge said. The victim "sidestepped" the would-be robber and ran off, according to Wedge.Less than an hour later, a knife-wielding man matching Scroggins' description approached a woman in the 500 block of Anita Street in Chula Vista, grabbed her and tried to pull her into a vehicle. The victim resisted, prompting a struggle during which the assailant stabbed her at least once in the arm, the captain said.The woman broke free and fled. She was treated at UCSD Medical Center in San Diego for non-life-threatening wounds.Shortly before 2:30 p.m. Wednesday, Scroggins allegedly stole a young woman's purse in the area of East 30th Street and B Avenue in National City, and then fled in a silver Nissan Quest.About 90 minutes later, a man grabbed a 13-year-old girl from behind and put a knife to her throat near Q Avenue and East 16th Street in National City. The girl, who suffered a cut finger in the assault, managed to elbow the abductor and run to a nearby relative's home.Thirteen-year-old Guadalupe Perez said she was walking home from National City Middle School when Scroggins jumped out and tried to grab her."He told me, 'Get in the car or I'm going to cut you,' and then I gave him an elbow hit and then I screamed. He let me go and he went back in the car and I went home," Guadalupe told 10News.She said she remembered a recent kidnapping attempt in Chula Vista where a girl screamed and ran to get away from a kidnapper."I'm like, 'This is really happening,' and then I thought of the girl that almost... and it worked," said Guadalupe. "I just think what would happen if I did do what he said. I might have ended up in a lake somewhere dead, cut in pieces. I don't know, I'm just grateful I did what I did."A license-plate number provided by the purse-snatching victim led police to Scroggins, who allegedly implicated himself in the earlier Chula Vista cases during an interrogation by National City detectives.Scroggins apparently traveled to the San Diego area after removing a location-monitoring ankle bracelet he had to wear in Napa County due to his sex-offender status there, according to police.He is listed as a transient on the Megan's Law website.