Sgt. Denis Ayres of the U.S. Park Police once chased a suspected car thief up the steps of the Capitol. So what, you say? Ayres was riding Timely Reward, a former race horse, at the time.

It's all in a day's work, says Ayres, who directs the mounted unit of the Park Police and has been a member of the force for 23 years. Now 47, he confides, "I'm two years past retirement, but I have no intention of retiring."

Ayres oversees the training of the 50 men -- seven are blacks, five live in D.C. -- and 70 horses, which are kept in seven stables across the city. "We get paid $800 more (annually than D.C. police)," one veteran observed, "but we use it all up in cleaning bills."

Equestrian duty includes everything from patroling the Mall to policing civil demonstrations where, according to Ayres, "One man on a horse is equal to 12 men on foot in working crowd control."

When they join the mounted unit, 90 percent of recruits have never ridden a horse.

"A lot of men think it sounds great because it's mostly day work," said Pvt. Greg Brown, 31, of Silver Spring. "But there's more to it than just sitting on top of a horse."

For a policeman to be considered for the mounted section, he must have been with the force at least three years, and most have served at least five years. "Last time we posted a notice, we had 73 applications for 15 positions," Ayres recalled.

Eight members of the force also ride in precision drills set to music, at horse shows and fairs. Five of the mounted park police are members of an equestrian drill team that competes at horse shows in Pennsylvania and the Washington area.

At the recent Washington International Horse Show, the United States Park Police won the Francis J. Hannan Memorial for team competition, and Ayres took home the coveted Joseph Hendrix Hines trophy for the best individual performance.

Candidates for the mounted section are given a reading list on horsemanship, then are interviewed and tested by a review board. Those accepted for training may weigh no more than 190 pounds, and must undergo nearly 500 hours of intensive instruction.

The first lessons cover the basics -- taking care of the horses. "It's called 'stable management,'", said Brown. "In reality, it's cleaning stalls and brushing the horses." Now in his third year with the unit, Brown admits, "I didn't even like horses in the beginning."

Stable management is followed by lessons in basic horsemanship -- learning to sit the horse and control its gait. Pvt. Wayne Carroll, 32, of Morningside, Md., said when he joined the unit seven years ago, "I didn't even know which side to get on from. I was a little hesitant at first, but I've learned to love it." Now he helps train new horses.

Most of the horses used by the force are donated. A horse is accepted for a 30-day trial, and must pass a veteranarian's examination.

The training period for the horses is the same as for the riders -- a total of 480 hours. The first day a new horse is brought in, he is ridden quietly indoors. The rest of the first week is spent in Rock Creek Park, where he gets his first exposure to children. This is a very important aspect of his training, since children love to pet police horses.

The second week, the horse is taken into the Georgetown area. "A city setting, but not too intense," Ayres explains. During the third week, the new horse is taken down bustling K Street. "We want him to go right into this area. If the horse blows up at this point and doesn't settle down in one day, then we know we have a problem. Chances are slim we will keep him." Ayres says about three new horses out of 10 don't pass the test.

The new horse spends his fourth week on the Mall, and his next two months are "nothing but exposure to different places around the city," according to Ayres, who also travels to other cities to assist in the establishment of other mounted police units.

After three grueling months of training for both man and beast, the rookies hit the streets.

Ayres scouts the countryside for prospective four-footed members of the force. He found Timely Reward, his favorite, in a pasture in Middleburg, Va. In his racing days, Timely Reward ran 10th -- in a field of 20 -- in the 1951 Kentucky Derby, and then ran over jumps as a steeplechase horse. Ayres rode him in the funeral procession for President John F. Kennedy, and the two were partners for 13 years.

"He seemed to love it -- he took to the police work from the very first day," Ayres says of Timely Reward. Five years ago, when the horse could no longer put in an eight-hour day, he was retired to a government reservation, where he died six months later. Now Ayres rides Chili Multi, a former show horse.

"People look up to the policeman on a horse," Ayres says, "He's no longer a cop -- he has a horse, and that makes him special. It's a powerful image. And if things get out of hand, and the man on the horse tells someone to stand back or get away, no one is likely to talk back to the cop on the horse."

Oh yes -- the arrest on the Capitol steps. Ayres had radioed ahead, and when the suspect tried to duck down a corridor, another officer was their waiting to make the collar. These "mounties" usually get their man, too.