A 22-year-old man who is being charged with conducting three sexual assaults, which occured in September and October around Davis Square and Tufts University, was arraigned in Somerville District Court Friday morning.

Alfredo Romero Posada is being held in custody pending a "dangerousness hearing," scheduled for Nov. 22, to detemine whether or not he should be placed in pretrial detention, according to Middlesex District Attorney Spokesperson Jessica Pastore. 

Posada is charged with three counts of assault with intent to rape and three counts of indecent assault. He  is accused of perpetrating sexual assaults on Sept. 10, Sept. 24 and Oct. 22.

Those attacks are part of a series of six sexual assaults that have taken place around Davis Square, Porter Square and Tufts University since Sept. 10. (Somerville Patch recently, and incorrectly, put the number of attacks at five.) 

The Sept. 10 assault occured on Wallace Street near Davis Square, the Sept. 24 assault took place on College Avenue near Professors Row, according to a prosecutor speaking in court Friday, and the Oct. 22 incident took place on College Avenue in Medford.

The most recent sexual assault took place Nov. 17, at about 1:30 a.m., outside Porter Square. Another took place Oct. 20 near Porter Square, and there was also one on Oct. 2 on Orchard Street, near Davis Square. It is not known if Posada is also a suspect in those attacks.

In proceedings before Judge Neil Walker, Ceara Mahoney, an assistant district attorney in Middlesex County, told the court Friday the three victims in the Sept. 10, Sept. 24 and Oct. 22 sexual assaults identified Posada as their attacker during a Nov. 17 police lineup.

Mahoney described a pattern of harrowing attacks in which Posada allegedly approached women from behind, groping them, grabbing them, putting his hands under their clothing and pushing them to the ground or up against trees.

The assistant district attorney also described a police operation in the Davis Square area in which an undercover female detective posed as a victim. The prosecutor told the court Posada was seen to approach the undercover detective from behind, in a manner similar to those described by other victims. Police also observed Posada approach other women in the Davis Square area, the prosecutor said.

Posada allegedly told his lawyer he suffers from schizophrenia, according to Mahoney. He stood silently during Friday's court appearance and listened to the proceedings through the help of an interpreter.