A second suspect has been apprehended in a string of 20 sexual assaults that have taken place in Brooklyn since March, according to the police.

Joshua Flecha, 32, from Queens, was arrested on early Monday for criminal possession of marijuana and later picked out of a lineup as the alleged assailant in a May 7 incident.

He allegedly approached a 37-year-old woman as she swiped her Metrocard at the 8th Avenue entrance to the F line in Park Slope, Brooklyn. He grabbed her breasts, and exposed and touched himself inappropriately, police said.

They added that additional lineups in connection with other incidents in the pattern were being conducted on Tuesday.

In South Brooklyn, 20 women have been attacked from March 11 through October 13, according to the police. One was raped in June in Sunset Park, while others were groped.

Last week Adolfo Martinez, 26, from Sunset Park, was arrested and charged with sexual abuse and forcible touching in connection to one of those attacks, which occurred on October 10.

The police said the patterns of sex crimes may involve as many as four suspects.