So, I clicked on your link and there was no article. I saw a picture of a forelorn woman, and the back of another woman's head, and responses/replies from Yahoo members. The top of the page says "Yahoo News India", and you say Texas...
Not having more info, I wonder if this was a real event that happened in Texas, was it something that happened in India, were the students legal adults as you say, and so on...? I'm sure I could come up with more questions.
I can also offer an "answer" to your question.
What crime was committed? Is Texas still so backward that sex between CONSENTING ADULTS can still be a crime?
Even if the students are eighteen or older, many people in today's society see an authority figure such as a teacher, minister/Priest, parent, grandparent, boss, etc., having sex with a student/young adult of whom they were in a "position of power" over as "wrong". Morally wrong, at least.
Let's break this down a bit. If the eighteen year old is still a student and said teacher is their
teacher, there's a conflict of interest here. Did the student receive "A"s? And if so, did they earn the grade on their own merit? Is the teacher nice to ____________ (the student they are having sex with) but mean to _____________ (a student who turned down the teacher's advances and/or someone not deemed "attractive enough" to receive teacher's attention)?
We also have the element of "teacher accused of having group sex with students on video
". Were the students aware of the video taping or was their privacy violated?
On a side note, as a story idea, it's hot! Who cares about the "whys" the teacher was busted. Write a story from the teacher's or a student's point of view and how much fun they're having!