BOSTON (AP) — To high school classmates, Michael McDermott was Mike Martinez, a gregarious class clown with a love for acting and a sense of the dramatic.

But in the years since, he'd changed his name, worked on a nuclear submarine, divorced — and became known to some as an eccentric loner with few close friends.

These starkly different views of McDermott collided this week as he stands accused of killing seven of his co-workers at Edgewater Technology Inc.

Prosecutors say McDermott, 42, apparently angry over a demand by the Internal Revenue Service to garnishee his wages for back taxes, methodically stalked through the office and gunned down four women and three men, some as they desperately tried to escape.

Then, prosecutors said, he sat impassively in the office lobby until police arrived. As they approached, McDermott's only words were cryptic: "I don't speak German."

Nearby was a stash of weapons: a semiautomatic assault rifle, a 12-gauge shotgun and a pistol.

McDermott is being held without bail after pleading innocent Wednesday to seven counts of murder.

The Friday before the killing, co-worker Robert O'Leary told The Boston Globe, McDermott gathered two colleagues as witnesses at his desk and had them sign his will. No one wondered why.

Those who knew McDermott in high school, when he was known as Mike Martinez, were in disbelief.

"He was a very nice guy, everybody liked him," said high school classmate Kurt Schulter. "He was always in a good mood. This is completely shocking to me."

A co-worker who spoke under the condition of anonymity said McDermott went by the nickname "Mucko" — something his nieces and nephews came up with when they couldn't pronounce Michael. He even had it on his license plate.

McDermott was born Michael McDermod Martinez in Plymouth to Raymond and Rosemary Martinez, according to town records. He changed his name, the Globe reported, because he wanted to sound Irish, not Hispanic.

McDermott grew up in Marshfield, a seaside community of 21,000 about 28 miles south of Boston where his parents worked as teachers.

McDermott attended Marshfield High School, graduating in 1976. In his yearbook photo, he's wearing a natty turtleneck and his hair is short and wavy — in stark contrast to the long, unkempt hair and beard McDermott now sports.

Schulter said McDermott was always joking, and participated in the drama club. In the class will, McDermott said he was leaving "stage left."

In 1978, he joined the Navy, and he served six years aboard the nuclear submarine USS Narwhal. He was an electrician and was honorably discharged as a petty officer second class.

Shipmate Bruce Joy said he wasn't surprised to learn that McDermott had been arrested in the shooting. Joy recalled an episode when several shipmates angered McDermott, and he lashed out with a knife, cutting Joy's leg. McDermott later apologized.

"If you violated his space, or didn't respect him as a person, didn't show him respect, he could react in ways that would surprise you or shock you," Joy told the Patriot Ledger of Quincy.

However, Jack Semelsberger, his superior officer on the submarine, described McDermott as "a fun guy, not a troublemaker."

McDermott's post-Navy life included a marriage to Monica Sheehan in early 1990s that ended when the pair separated after 3« years. Sheehan did not immediately return calls seeking comment.

He also worked in research and development for nearly 10 years at Duracell, where he left voluntarily in February, according to Eric Kraus, a spokesman for Gillette, which owns Duracell.

Marcus Scott, a co-worker at Duracell, described McDermott as inquisitive and sociable.

"I can't believe this," Scott told the Globe. "That the man would just walk in and start shooting people. Mike wouldn't do this. Mike wouldn't hurt a fly."

In October, McDermott moved from Weymouth, where he'd lived at least nine years, to Haverhill, about 35 miles north of Boston. Investigators seized bomb-making chemicals, blasting caps and magazines on explosives from his Haverhill apartment.

His job at Edgewater began in March, and co-workers there viewed McDermott in vastly different ways.

After Tuesday's shooting, co-worker Mike Stanley described McDermott as "a little strange" and "quirky," offering that if any of his co-workers was capable of the rampage, it was McDermott. But Frank Harrington, a consultant at the company, had another take.

"I thought he was, prior to (Tuesday), a nice person to work with," he said.