The Washington Redskins added a linebacker to their defense and $6 million to their payroll yesterday when the Chicago Bears decided to pass up free agent Wilber Marshall.

Marshall -- fast enough to cover wide receivers and certainly strong enough to bench-press one -- signed a five-year, $6 million offer sheet one week ago with the Redskins, an agreement that included a $500,000 signing bonus, a no-trade clause and a guarantee in case of injury.

The Bears had seven days to match it and retain their two-time Pro Bowl linebacker, but team president Michael McCaskey said yesterday he feared a revolt from his other players -- who almost all would want to renegotiate -- and let Marshall leave.

As compensation, the Bears will receive the Redskins' No. 1 college draft picks in 1988 (last in the first round) and in 1989.

"We've been without it {the No. 1 pick} before," Redskins General Manager Bobby Beathard said last night. "We're still excited about the draft."

Marshall, who will be 26 in April, not only becomes the highest-paid defensive player in the league (New York Giants linebacker Lawrence Taylor will earn $1 million in 1988, and Marshall makes $1.4 million this season with his signing bonus), but the first free agent to switch teams since defensive back Norm Thompson moved from St. Louis to Baltimore in 1977.

In professional basketball, baseball and hockey, free agency movement has been more frequent, although not without controversy. In baseball, for instance, the owners have been found guilty of collusion.

"I never thought I'd make this much," Marshall said yesterday from his parents' home in Titusville, Fla. "My folks and I, we thought $30,000 or $40,000 would be a lot to live off of. Now, I'll about get that in a week."

"It was a tough decision," McCaskey said in a statement released by the Bears. "However, we looked carefully at our options and are unified in our position."

Another factor in their decision was a unique clause in Bears linebacker Mike Singletary's new contract.

Sources said Singletary signed a deal last season worth approximately $750,000, but it also stipulated that he continue to make the most money on the team. So, if the Bears had kept Marshall, they would have had two $6 million contracts to work with, not one.

There has been some speculation that the NFL actually welcomed Marshall's signing, because it would help the league's upcoming court case against the National Football League Players Association, which is suing the league for violating federal antitrust laws.

"What precipitated this whole thing?" attorney Bob Woolf asked yesterday. "So many years with no offers, and suddenly {the Redskins} make this extraordinary deal? We don't know if it's because litigation is pending or if this is really a sincere effort to make free agency what it's designed to be."

On the other hand, Marshall's agent, Richard Bennett, of the Washington-based Bennett and Owens Sports Management firm, said yesterday he initiated talks with the Redskins, just a day after Washington's Super Bowl victory over Denver. Yesterday, he recreated his conversation with Beathard:

"I said, 'Bobby, Wilber Marshall would like to play for you, and I don't have to tell you he's a great football player.' Bobby said, 'We'd love to have him,' and I said, 'Would you draw up an offer sheet and give up two first-rounders to get him?' He said, 'Let me think about it and talk to Mr. {Jack Kent} Cooke and Coach {Joe} Gibbs.' I was waiting for the other shoe to drop. I kept thinking something would go wrong."

At one point, Bennett said the deal "was dragging on," and he wondered if he might have to see if other NFL teams wanted Marshall. The Redskins, he said, did not want to draw up an offer if the Bears would simply match it, but Bennett included the no-trade clause, the injury guarantee and the signing bonus to make the Bears waver.

Beathard, who learned of the Bears' decision while making a call in a telephone booth at a Colorado ski resort, said he gets "numerous calls" from representatives of free agents each season.

"I don't remember what my feelings were," he said of his first conversation with Bennett. "Each year, teams go over veteran free agent lists and size it up to see how they can help their team. We've looked at free agent lists every year. This just happened to be the year we did something."

Team owner Cooke was not available to comment late yesterday, but he told United Press International earlier that "Wilber Marshall adds another mark of quality to the world champion Redskins."

San Francisco 49ers owner Edward DeBartolo said yesterday he might just follow the Redskins' lead.

"It doesn't take a rocket scientist to know we're looking for somebody who can get sacks," DeBartolo told the Oakland Tribune. "We're looking for linebackers."

Linebacker Carl Banks of the New York Giants is a free agent, as is linebacker Andre Tippett of the New England Patriots. Banks, who made the Pro Bowl this season, was only the 44th highest paid linebacker in 1987, earning $300,000. And sources said the 49ers are interested.

Marshall has played right outside linebacker since joining the Bears out of the University of Florida in 1984, but he also played the middle during passing situations. He said he will go where the Redskins want him to go.

"I'll prove to them I'm worth every penny and help them go to another Super Bowl," Marshall said yesterday. "That's my goal. Listen, all {the Redskins} have to do is sit back and watch. I can't wait. I'll be there next week to get things started, to find me a house."

The son of a carpenter, he specializes in interior decorating, and has made elaborate designs inside his current home in Lake Forest, Ill. Current Redskins wide receiver Art Monk is a good friend of Marshall's, but Marshall also understands his large contract could bring resentment from other Redskins players.

Previously, quarterback Jay Schroeder was the highest paid Redskin ($900,000 in 1988), but Marshall also will make $900,000 this coming season if you don't count his signing bonus, and in 1989, Marshall will make $1 million, the salary then increasing $100,000 each season through 1992.

"It'll be tough to earn {the other Redskins'} respect after what's happened with my contract," Marshall said. "But it's a situation the owner decided to do. It wasn't my decision. Sure, people will feel funny, but I'm sure when their time comes, they'll do well."

So far, it's too early to say whether other Redskins will demand larger salaries. Defensive end Dexter Manley will make $405,000 this season, and Woolf, his attorney, said yesterday: "Oh boy, it's going to be fascinating to see what happens, to see how players and their representatives react. We'll wait and see."

Bennett also represents Redskins linebacker Monte Coleman, who was last year's right outside linebacker, the position Marshall could play. Coleman is a free agent as are 15 other Redskins, including defensive tackle Darryl Grant, center/guard Russ Grimm, running back Keith Griffin, guard R.C. Thielemann and cornerback Barry Wilburn.