A 61-year-old man who shot his 16-year-old autistic son to death last month, then shot himself, got his gun from a straw purchaser, authorities said yesterday.

Segundo Duque shot his son, Fabian, once in the head after pulling over in his minivan at Wyoming Avenue and H Street, in Juniata Park, on the morning of Nov. 9, police have said.

He then drove nearly two miles to Sanger Street and Loretto Avenue, in Summerdale, where he parked near St. Martin of Tours Roman Catholic Church and shot himself in the head shortly after 6 that morning, police said.

Yesterday, the District Attorney's Office said the 9 mm handgun used by Duque was purchased for him by Neisha Valle, 23, of O Street near Hunting Park Avenue, in Juniata Park.

Valle was one of 21 people investigated by the city-state Gun Violence Task Force, who were recently arrested or who are expected to be arrested on gun trafficking and related charges.

Duque, of Paul Street near Torresdale Avenue, in East Frankford, had shown signs of being drunk that morning, when he had first gone armed to the home of an ex-girlfriend. After an argument with the woman, during which he pulled his gun out, she escaped unharmed, police said.

It was later that morning when he shot his son, then killed himself, police have said.

Valle faces a March 10 preliminary hearing on tampering with public records and gun charges.

Since the task force began in December 2006, it has opened 1,207 investigations, made 395 arrests and seized 743 firearms. To date, 157 people have been convicted of gun-related offenses.

District Attorney Lynne Abraham said in a news release that the success of the task force - combined with her office's legislative efforts and the First Judicial District's gun court - has resulted in fewer homicides and fewer gunshot injuries.

Others recently arrested were:

* Linda Woods, aka Deborah Cromwell, 53, of Bouvier Street near Erie Avenue.

* Ilisabeth Neerenberg, 37, of Rosewood Street near Ritner.

* Lawrence Washington, 26, of Sigel Street near 22nd.

* Lakisha Lewis, 25, of Leiper Street near Dyre.

* Omar Bulli, 27, of Woodbine Avenue near 76th Street.

* Uranus Ladson, 42, of 4th Street near Reed, and Tyrneika Brown, 22, of Darby.

* Jayson Miller, 29, of Hortter Street near Ross.

* William Stewart, 55 of Berks Street near 54th.

* Jack Belani, 25, of Norristown, and Wenjue Liu, 26, of Yardley.

* Anthony Poindexter, aka Francis Furr, 32, of Cross Street near 6th.

* Patrick Kersey, 20, and John Cooper, 28, both of Vandike Street near Hellerman.

* Adiyah Weston-Eskridge, 31, of 55th Street near Wyalusing Avenue.

* Raoul McDaniels, 39, of Mount Pleasant Avenue near Provident Street.

* Simir Boyd, 21, of 22nd Street near McKean.

Meanwhile, arrest warrants have been issued for:

* Tyree Berry, 24, of Saybrook Avenue near 72nd Street.

* Danielle Demaio, 24, of Gratz Street near Wingohocking.

* Maurice Boykin, 26, of Latona Street near 32nd.