The security guard in the lobby of the Los Angeles Times couldn't help but ask the question. When he looked at the computer in front of him earlier this week, he saw the picture of a strapping blond man. The screen identified the employee: "Michael Penner, Editorial."

But the person flashing the ID was a tall woman, with long, strawberry blond hair. "Ma'am, whose card are you using?" the guard asked. The subject moved closer to answer quietly: "I'm Mike Penner and I'm a transitioning transsexual."

With that, security waved Penner into the newspaper where he has worked for 23 years, one of many hurdles the veteran sportswriter will be crossing in the coming weeks as he transforms into Christine Daniels.

Penner, 49, shocked many readers, fellow journalists and sports fans with a column in Thursday morning's Times Sports section that told the world of his decision to switch genders.

The revelation drew an enormous response -- with the highly personal 823-word essay becoming, by mid-evening, one of the most heavily viewed stories on latimes.com in the last year, with about half a million page views.

Although some readers criticized Penner's decision and the way the newspaper announced it, the vast majority of those e-mailing and phoning The Times on Thursday said they supported the writer and the paper for letting him tell his story.

"Writing that piece, which I didn't initially want to write, ended up becoming one of the best things I have ever done," Daniels said in an interview Thursday. "And a day I dreaded all my life has ended up being one of the best days I've ever had."

As Mike Penner, the journalist covered beats as diverse as professional baseball's Angels, the Olympic Games, soccer's World Cup, tennis, the NFL and sports media. After a break of a few weeks, the reporter's next stories will appear under the Daniels byline, the new surname derived from his middle name at birth -- Daniel.

She will be writing a blog about Southern California sports. Latimes.com also plans to give Daniels space to write about the experience of a gender transformation under the tentative heading "Woman in Progress."

Daniels wore pants and a green flowered blouse during the interview, along with the wig she is wearing while her hair grows out.

Wearing light makeup, muted lipstick and a trio of bracelets on one wrist, she pronounced herself tremendously relieved at shedding the male persona that made her feel trapped most of her life.

Daniels said she had felt since she was 4 or 5 years old that she was a girl. She liked dolls and wanted to wear dresses. An initial interest in sports began when she saw a display of the colorful uniforms of the old American Football League teams.

"I spent my whole life with nose pressed against the window thinking, 'Why can't I get to the other side?' " Daniels said. "I thought it would be so much easier for me" to be a woman.

"It came to the point ... even though you are scared to death, you have to try to change, because staying the same is even more difficult."

Daniels said she had experimented with wearing women's clothes for years but went out in public for the first time only two or three years ago. Working largely at home on the Sports section's Morning Briefing column, the writer did not have to worry about how she dressed.

She began dressing full time as Christine in January, at roughly the same time her doctors put her on hormones.

Not all transsexuals have surgery to complete their sexual transformation, and Daniels said it was "too early" and "fairly private" for her to say publicly what she might do.

The story will undoubtedly raise many more questions. The Times turned down multiple interview requests -- from ABC's "Good Morning America," ESPN radio, the BBC and CNN's "Larry King Live," among others -- on the writer's behalf.

By early evening, nearly 1,000 readers had commented on the story on latimes.com. The responses posted on the message board were overwhelmingly positive.