NEW YORK (Updated 2:34 a.m.) - As security head at Morgan Stanley Dean Witter, Rick Rescorla knew the drill: He had ferried employees out when terrorism first struck the World Trade Center in 1993, and he was there with his bullhorn Tuesday, trying once again to get his people out.

Nearly all of them did. Rescorla did not.

He's one of the 15 Morgan Stanley employees still missing. And those who know him say that Rescorla, who was in his 44th-floor office in the trade tower struck by the second plane, may well be the reason the vast majority of the 3,700 Morgan Stanley employees got out alive.

"Rick was down toward the base trying to make sure people got down and out," said Bob Sloss, a managing director at Morgan Stanley who last saw Rescorla around the 10th floor in the stairwell. "He was definitely there well after it had been established that the building was in trouble."

Typical Rescorla, said those who know him from his days as a lieutenant and platoon leader in Vietnam, where he would sing to his men at tense times and instill in them the courage to get back up for one more round of battle.

"He couldn't be any other way," recalled Sam Fantino, who was Rescorla's radio operator in Vietnam and has been flooded with e-mails from their military colleagues bemoaning the possible loss of Rescorla, 62, in the World Trade Center tragedy.

Morgan Stanley employees remembered stories of how Rescorla had bounded into action during the 1993 bombing at the trade towers. Fantino said Rescorla took a rather unconventional approach to regaining control of the panic-stricken crowd as he tried to clear the building that day.

"To get their attention, he dropped his pants," recalled Fantino. Rescorla, with his commanding demeanor and booming voice, was just the type you want in charge, whether it was on Tuesday or during the 1993 attack, Fantino said.

"He was literally the last person to leave that building," another Army friend, Joe Galloway, recalled of the 1993 bombing. "He stayed until he had gotten everyone out, and that is the nature of the man."

Born in Hayle, Cornwall, in England in 1939, Rescorla served as a mercenary for British Army forces in Zimbabwe, and then became a police officer in Rhodesia before coming to the United States in the early 1960s and joining the Army.

He was a platoon leader in Vietnam, where Fantino and others said Rescorla was an inspiration to his troops. He could make them laugh with a joke or a song, and somehow inspire them to get up and "kick some butt" in battle.

He put himself through college at Oklahoma University on the G.I. bill, and went on to get a master's degree and a law degree. Rescorla, who retired as a colonel in the Army Reserve in 1989, had worked in security management for many years, including the past 18 working for Morgan Stanley, where he started out as director of security and moved up to first vice president for security.

Spread between the 43rd and 66th floors, Morgan Stanley offices were buzzing with activity Tuesday when the first plane struck the neighboring tower at about 8:48 a.m.

A plane hit the second building about 9:10 a.m.

Rescorla was in his office when the disaster hit.

His wife, Susan, said she called when she heard the news and was told, "Don't worry about anything, Rick is getting the people out."

Rescorla called about 10 minutes later. His next words struck terror in her heart: "If anything happens to me," he just wanted her to know that "you made my life."

She said she's heard that her husband was going from floor to floor, making sure people were out, and had been spotted around the 72nd floor at one point. Since then, she's been praying constantly for some shred of evidence that he might somehow be alive, caught in the rubble.

Sloss, who was in his office on the 66th floor when the plane hit, said he remembers seeing Rescorla somewhere around the 10th floor, shuttling people along the way, telling them to get off their cell phones and proceed carefully but quickly.

"Rick was down there absolutely perspiring," said Sloss. "He had his bullhorn. He was encouraging people to calm down."

"If anybody could get (people) out or do anything," his wife said, "it was my Rick."