Mary Reeves, a Trenton housewife and mother gripping a furled umbrella and wearing a red beret, took her place in the line of lean, bead-and-feather bedecked Guardian Angels as they set out on foot for Washington this week.

Walking in front of the pine coffin the anticrime volunteer group carried to honor a fallen comrade, Reeves lasted three miles before dropping out. But as a more famous marcher, Gen. George Washington, did a few miles from here more than 200 years ago, Reeves figured she was taking a step for civilization, at least as she knows it.

"Trenton is my city and the Guardian Angels is what's going to keep it my city," she said.

Reeves was one of those who turned out to support the 50 Guardian Angels as they began their 170-mile march Thursday to demand a federal inquiry into the death of member Frank Melvin, shot by a Newark policeman Dec. 30. They hope to meet Attorney General William French Smith to demand that a special prosecutor investigate the death. Smith has not said whether he will meet with the group.

Police say Melvin was shot from a rooftop by a Hispanic officer, who thought the Angel was threatening his partner on the street below.

Angels claim that a white police officer did the shooting from close range on the street. Angels accuse police of trying to cover up the incident to avoid racial violence.

The Angels decided to march on Washington after a 50-mile-trek from Newark to Trenton failed to convince New Jersey's attorney general to appoint a special prosecutor.

Today the Angels headed out from New Castle, Del., toward Aberdeen, Md. Describing the hike in icy temperatures as "physically tough," Angels leader Curtis Sliwa said many marchers were suffering from sores, frostbite and twisted ankles. The group hopes to pick up new marchers along the way and reach Washington by mid-day Tuesday.

[The bitter cold tonight forced the Angels temporarily to halt their march, United Press International reported. As temperatures dropped to about 10 degrees, Sliwa said Red Cross volunteers examined the marchers near Aberdeen and told many of them to give up the trek because of possible frostbite.]

[Several marchers rode in a van 10 miles to Aberdeen, where they were to resume the march Sunday. The remaining two-thirds of the group of 50 abandoned the march and went to Philadelphia. They were to be replaced by Angels members from New York, Sliwa told UPI.]

Among those who earlier said he planned to walk all the way was Philadelphia Angel Epi Romano, 18.

"It's a magnificent cause," he said.

"The Angels give the kids on the street something to look to that is positive, not the stealing and the drugs and getting high."

For Myrna Izarry, 19, of Newark, the trip was a memorial to a friend. Izarry lives in the housing project where Melvin resided, served in the Angel chapter he organized and was present the night he was killed.

"Frankie was my friend," she said. "I want people to know how he changed things."

The Guardian Angels, which Sliwa started in 1979 to stop crime on a New York subway train dubbed the "Muggers Express," have grown to an estimated 2,200 members in 33 cities. Founder Sliwa has become a celebrity. Feelings about the Angels run strong in New Jersey.

At Melvin's funeral, Sliwa eulogized him as "a great American hero, a man who turned it all around.