Defensive tackle Bob Slater, the Washington Redskins' top draft pick a year ago, has undergone reconstructive knee surgery and is expected to miss his second consecutive season.

"It will be another long year," Slater said by telephone yesterday from his bed at Sibley Memorial Hospital. The interior cruciate ligament in his left leg was rebuilt there Tuesday after a series of injuries in the last nine months.

"I think the doctors finally feel they have nailed the problem down and corrected it," Slater said.

The news -- glumly announced yesterday by Coach Joe Gibbs after the veterans' first minicamp practice -- added another name to the growing list of players who may not return to the team, for a season or for a career.

General Manager Bobby Beathard already has held "preliminary" talks with several NFL teams that may be interested in obtaining two-time all-pro wide receiver Charlie Brown, who is skipping the minicamp and is not expected to return to the team.

Brown, who was not returning phone calls yesterday, is said to be upset over several things, including his lack of playing time last season, when he caught just 18 passes and was hampered by injuries.

A trade, Gibbs said, "would be the next step" if negotiations continue to fail.

"There's still a chance things could work out, but I'm not very optimistic," Gibbs said.

Beathard expects that Brown would command a high price on the trading block.

"I would think with a player of his caliber, there would be a lot of interest," Beathard said, beginning to smile. "We should get something of equal value . . . like a Pro Bowler."

A first-round draft pick, he said, is more likely.

The Redskins also could trade veteran free safety Mark Murphy, another minicamp holdout who has been engaged in a contract dispute for several months. However, it is much more likely there will be no trade and that Murphy will enroll in law school, probably at Georgetown University, this fall.

When reached at home yesterday, Murphy, 29, said his plans are to go to law school, "making some assumptions (about not playing football again)."

He refused to comment on what, if any, negotiations were on-going with the Redskins. Murphy, who lost his starting job when he missed nine games with a knee injury last season, wants some or all of his contract to be guaranteed. He also is concerned about playing time, according to sources.

The Redskins expected Murphy's absence, but Brown's caught them by surprise. As late as last week, Brown was working out at Redskin Park, and only through "the grapevine" did Gibbs find out there were problems.

"You never know what he'll do," Beathard said. "It's too early to say if he'll decide to come back or not. In the meantime, we just have to protect ourselves (by looking into trade possibilities)."

The Redskins are not concerned about losing veteran defensive tackle Dave Butz, another minicamp no-show. Butz, a free agent who is home in Belleville, Ill., is expected to come to terms sometime soon.

"I've talked to him a lot, and I think it will work out," Beathard said.

The Redskins are not quite so confident about reserve defensive end Tom Beasley, who is not attending the minicamp because of contract problems. Without Butz and Slater, Gibbs said he had planned to work Beasley at tackle. Instead, reserve Perry Brooks and quite a few rookies and younger players are getting all the work.

Because of injuries, reserve cornerback Anthony Washington and reserve tight end Mike Williams also are not working out at the minicamp, Gibbs said. Washington, who twisted his knee two weeks ago while working out in California, will undergo an arthrogram on the knee today, head trainer Bubba Tyer said.

Williams, who missed last season with a neck injury, has a strained knee ligament, Tyer said.

Not all the news has been bad for the Redskins. Beathard announced that free agent cornerback Vernon Dean signed a series of one-year contracts, and that wide receiver Ricky Smith and offensive tackle Morris Towns, also free agents, signed one-year agreements. Free agent tight end Rick Walker has agreed to terms and is expected to sign soon, Beathard said.

In other developments, Beathard said reserve wide receiver Alvin Garrett, whose contract offer was withdrawn by the Redskins, has had a tryout with Philadelphia. Running back Rick Kane, also let go by the team, has been placed on waivers and might be picked up by Detroit, his former team.

Slater, the 31st choice in the 1984 draft, had worked up to 280 pounds, from 265, in the Redskin Park weight room, only to reinjure his left knee during an agility drill last Friday. Since last August, he has suffered a series of injuries, twists and turns to the knee that never had been injured before, he said.

The Redskins, who blamed a "breakdown" in communications for the two-day delay in releasing the news of Slater's operation, were upset they will have to go without Slater for another year.

"It's just so disappointing, for a guy who worked so hard in the off-season," Beathard said. "There's never a guarantee on something like that, but a lot of guys are playing who have had the same surgery. I'm optimistic on it. I think he will come back."

After spending six weeks in a splint, Slater said he expects to have six months of rehabilitation. He could be back in time for the playoffs, Tyer said.

In practice in the rain yesterday, running back John Riggins ran with the first team and experienced no pain or problems with his back or hip, Gibbs said . . . Working with the second team was quarterback Jay Schroeder; Babe Laufenberg worked next . . . Fifth-round draft choice Raphel Cherry has been working at cornerback and will get a shot at free safety, Gibbs said . . . Tenth-round pick Terry Orr, a running back at Texas, has been moved to H-back (man in motion).