Call it the Case of the Mystery Penalty.

The Redskins lost any chance of snapping their long losing streak today when a game-tying fourth-quarter touchdown against the Atlanta Falcons was nullified by a flag Washington players claim never should have been thrown.

"They (the officials) took it from us," fullback Clarence Harmon said after the Falcons' 10-6 victory, Washington's fifth straight loss. "They threw a flag, they didn't know what to call, so they wind up coming up with something that didn't happen."

The penalty in question came with 4:36 left in the game. With Atlanta leading, 10-3, quarterback Mike Kruczek, starting for injured Joe Theismann, completed a 24-yard scoring pass to receiver Ricky Thompson. But three flags were lying on the field: one penalty was called on Atlanta's Joel Williams for roughing the passer, one each on Atlanta linebacker Al Richardson and Washington tackle Terry Hermeling for exchanging head slaps. r

"Richardson? Who's he? I never heard of him. I was blocking (end Jeff) Merrow on the play," Hermeling said, angrily. "I never came in contact with Richardson.

"After the game, Merrow laughed about it. He said he knew nothing happened.

"On the play, my guy had an inside move on and I drove him over the top of the pile and fell on top of him," Hermeling said. "There was no shoving, no slapping. I never heard of that call before. It was absolute bull."

After the game, referee Ben Dreith said, "The umpire (Bob Boylston) had a man from Washington and a man from Atlanta exchanging blows or swinging at each other and hitting each other. The referee had roughing the passer on No. 58 (Williams) on the defense, so there were two personal fouls on one team and one personal foul on the other team. So, by rule, you have to play the down over."

Harmon said he was standing behind the officials when the penalties were being discussed.

"They couldn't decide what to do, so they finally said, make it a personal foul on both teams," Harmon said. "How can Terry do it (head slap) when he was cut-blocking his man? They didn't know what to call, they just wanted to call something on us. We needed that touchdown. It would have really picked us up."

Instead, the Redskins now can relive another crushing loss in an already maddening season. But this one hurt perhaps more than any of the previous nine defeats, judging from the sadness afterward in the locker room.

"A new way to lose a game," Coach Jack Pardee said, shaking his head before adding, "an offensive head slap. I guess when things go wrong, they can go in strange ways. It's the first time I've ever heard of that penalty."

Until Thompson's touchdown was wiped out, Washington had executed Pardee's ultraconservative game plan almost to perfection. The defense had held the high-scoring Falcons to one touchdown, the special teams were outplaying their Atlanta counterparts and the offense was staying away from the killing interception or fumble late in the game that would have put an upset out of reach.

Going into today's game, Pardee was content to win on Mark Moseley's field goals. Moseley came through with 51- and 46-yard kicks, but two other chances were eliminated in the first quarter by a Kruczek interception at the Falcon 21 and Wilbur Jackson's fumble at the Atlanta 11. Kruczek fumbled away the ball at the Redskin 47 later in that period.

"We had a chance to jump way out in front early," Pardee said. "We aren't a team that can make those kind of turnovers. We had to at least get field goals from those opportunities and we came up with nothing. It doesn't matter if the mistakes come early or late, you just can't have them, especially in our condition, if we want to win."

For the second straight week, the Redskin defense played impressively.Last Sunday, it held Dallas, the NFL's top-rated offense, to 14 points. This time, it limited the Falcons to their second-lowest output of the season. The unit played well enough for the Redskins to win, making the defeat even harder to take.

Still, the Redskins led at the half, 3-0, the first time they had been in front at intermission in six weeks. Quarterback Steve Bartkowski finally solved Washington's multiple defensive coverages long enough to put Atlanta ahead, 7-3, on its first possession of the third quarter, but the Redskins stayed within reach and never let the Falcons get completely untracked.

Bartkowski finished with decent enough statistics -- completing 14 of 32 passes for 219 yards, with one touchdown and one sack -- but those numbers were misleading. Against an aggressive, blitzing opponent, he misfired seven straight times during one stretch of the first half and didn't make his second completion until seven minutes had gone by in the second quarter.

While he was struggling, however, Washington couldn't knock out the Falcons. That gave Bartkowski a chance to recover in the second half, once his line began picking up the blitz and he could take advantage of the Redskins' man-to-man coverage in the secondary.

He connected on four passes in a row in that third-period scoring drive, which ended on a 14-yard throw to Alfred Jenkins. Then he set up Tim Mazzetti's 23-yard field goal in the fourth period with passes of 18 and 17 yards to Jenkins, who had six receptions for 91 yards.

Otherwise, Atlanta averaging almost 30 points a contest, was held at bay so well that its only other chance to score was on a field goal of 47 yards that Mazzetti missed.

Washington's pop-gun offense was even more inept. With Kruczek playing, the Redskins all but eliminated any plays that even remotely could be considered daring. They were content to play for field position, run the ball often and try an occasional short pass. Washington finished with 193 total yards, its lowest output of the season.

"Joe not being in there limited us somewhat," Pardee said. "When your No. 1 quarterback isn't there, it has to hurt you. It's tough for a backup quarterback to come in and play a team like Atlanta. Mike isn't used to reading keys and delivering the passes. But we were still playing to win, not just to keep it close."

Kruczek completed 14 of 18 passes for 127 yards, 41 of which came on one throw to Art Monk. Pardee left no doubt afterward that once Theismann's sore hamstring heals sufficiently, he will return to the starting lineup, perhaps this week against San Diego.

The Redskins have scored only 51 points during the five-game losing streak.

And for the fourth time this season, they were held without a touchdown. It now seems as if Pardee almost has given up on trying to get into the end zone with any regularity. If Washington is to win again this season, it apparently will be on the strength of Moseley's kicking.

Moseley's first field goal today came after Atlanta ran into punter Mike Connell to allow the Redskins to keep possession late in the first quarter. Moseley connected from 41 yards out, but linebacker Monte Coleman was hit with a 10-yard penalty for illegal use of his hands. So Moseley then drilled it from 51 yards and a 3-0 Washington lead with 10:14 to go in the half.

Earlier, Mike Nelms had returned a punt 64 yards to the Falcon 29, where he was downed by punter John James. But Jackson had the ball knocked out of his hands on a run up the middle, stopping the threat, just as Kruczek's forced pass to tight end Rick Walker was intercepted on the Redskins' opening possession to kill a drive at the Atlanta 21.

The Redskins threatened again after the Falcon touchdown. Nelms ran 51 yards to midfield with the kickoff, but Washington couldn't pick up even a first down before Connell had to punt.

Otherwise, the aroused Falcon defense kept its foe under control until Mazzetti's field goal put them ahead, 10-3, with 9:04 left in the game. Kruczek quickly got his team into scoring position when he evaded a heavy rush and hurled a high lob pass to Monk, who leaped to outfight two defenders for that 41-yard completion at the 24.

Two plays later, Thompson ran a go pattern and got behind the secondary. He gathered in Kruczek's pass in the end zone as the Redskin bench went wild. But then came the flags and Washington had to settle for Moseley's 46-yard kick. Atlanta proceeded to run out the clock for its seventh straight victory.

"Atlanta was ready to be beaten if we could have played a better game," Pardee said. "I felt we needed to make a play or two in this one to win it, and that touchdown pass might have been it.

"One of these days, maybe we'll play well enough to get rewarded with a victory. That's all you can hope for now."