Harvard has forced dozens of students to leave in its largest cheating scandal in memory, the university made clear in summing up the affair on Friday, but it would not address assertions that the blame rested partly with a professor and his teaching assistants.

Harvard would not say how many students had been disciplined for cheating on a take-home final exam given last May in a government class, but the university’s statements indicated that the number forced out was around 70. The class had 279 students, and Harvard administrators said last summer that “nearly half” were suspected of cheating and would have their cases reviewed by the Administrative Board. On Friday, a Harvard dean, Michael D. Smith, wrote in a letter to faculty members and students that, of those cases, “somewhat more than half” had resulted in a student’s being required to withdraw.

Dr. Smith, the dean of the Faculty of Arts and Sciences, wrote, “Of the remaining cases, roughly half the students received disciplinary probation, while the balance ended in no disciplinary action.” He wrote that the last of the cases was concluded in December; no explanation was offered for the delay in making a statement. The forced withdrawals were retroactive to the start of the school year, he wrote, and those students’ tuition payments would be refunded.

The Administrative Board’s Web site says that forced withdrawals usually last two to four semesters, after which a student may return.