Police also added six other attacks including this most recent one to the pattern, raising the number to 20 sexual assaults.
In Thursday's incident, the woman in her 20s, was attacked near Sixth Avenue and 17th Street as she walked her German shepherd mix at around 10 p.m.
Police say the suspect, armed with a knife, jumped out at her and grabbed her from behind. She screamed, and the suspect ran away.
The suspect apparently ditched his clothes, which were found nearby.
Meanwhile, the suspect charged with misdemeanor forcible touching and sexual abuse in Sunset Park, Brooklyn, is due in a Manhattan courtroom Friday to answer charges stemming from a 2007 groping in Chinatown.
Police say the man charged in Monday's sex attack, 26-year-old Adolfo Martinez, has admitted to groping other women, but they're not sure he is responsible for the string of attacks across the borough.
Martinez was arrested late Tuesday near his Sunset Park apartment building, not far from the scene of the attack. Police say the distinctive boots he wore matched what they had seen on a surveillance video. And when he was taken into custody and his apartment searched, investigators reportedly found the sweater worn during the attack.
However, Martinez' brother claims the suspect has been working in Canada for the past six months and cannot be responsible for earlier attacks. Police are still looking at Martinez as a suspect in the pattern of sexual assaults that started back on March 20 in Park Slope and quickly spread to nearby neighborhoods.