The case remains unsolved, but Yugoslavs' minds seem mainly made up on both incidents. They blame ethnic Albanians. They also blame them for continuing assaults, rapes and vandalism. They believe their aim is to drive non-Albanians out of Kosovo.

''A legitimized genocide against the Serbian people is being carried out in Kosovo,'' said Dobrica Cosic, a dissident novelist published here and in the United States, in an interview in Belgrade. ''More than 200,000 Serbs have been forced to leave their home in the last 10, 20 years.'' A steady exodus continues.

Since Albanian nationalists went on a rampage in 1981, leaving at least nine people dead, the level of violence has declined. But enough agitation continues, punctuated by acts of violence, to make a burning issue of the antagonism between the 1.4 million ethnic Albanians and the little more than 200,000 Serbs.

Under the federal Constitution, Kosovo is part of the Serbian Republic. In effect, it is as self-governing as the six republics of the nation. It is also the poorest region of Yugoslavia. Men in their 20's line the main street of Pristina - a stretch of grandiose modern buildings that separates near-slums on either side - offering to shine the shoes of passers-by who can hardly afford such luxury. Begging children accost diners in restaurants. Use of Funds Criticized

The overambitious buildings, such as a recent, prematurely rundown, 300-room hotel with 3 restaurants in a little-visited town of 100,000, sustain criticism of the provincial leadership a a misuse of federal development funds. To many, the aid represents a futile effort to solve an intractable problem through financial bounty.