6/11 11:26 AM PT -- The judge has declared a mistrial on the remaining 8 charges ... saying the jury was deadlocked and unable to reach a verdict.

It's unclear if prosecutors intend to retry the case.

Ex-NFL star Kellen Winslow Jr. has just been found GUILTY of forcible rape -- along with lewd conduct and indecent exposure -- and he's now facing serious prison time.

A jury deliberated in a San Diego courthouse for the past week before reaching a verdict Monday on 4 of the 12 counts he's facing ... finding Winslow guilty on 3 of the 4, including the forcible rape of 58-year-old Jane Doe #2.

He was also found guilty of indecent exposure to Jane Doe #3 and guilty of lewd conduct regarding Jane Doe #5.

He was found NOT GUILTY on a second lewd conduct charge regarding Jane Doe #5.

35-year-old Winslow was initially arrested back in June 2018. Officials say he kidnapped and raped 2 transient women in 2 separate incidents -- one in March and another in May.

A 3rd woman later stepped forward and also claimed Winslow raped her 15 years ago while she was unconscious.

Kellen was also accused of exposing himself to two other women in separate incidents over the past year as well.

All of Winslow's accusers testified during his trial -- which began on May 20.

Winslow had previously denied all the accusations ... insisting, "I am an innocent man" and called the whole thing a money grab.

The jury is going back into the deliberation room to discuss the 8 remaining charges.