One of my colleagues, who is a senior developer with 5 years at the company, works on things I am responsible for but usually ends up breaking things. I get blamed for it because I am responsible for this area.
Recently, he totally denied our 1-1 meeting on the issues I raised to him. After 2 days of waiting, thinking I would be notified, I was told to consult our manager, who he told those issues are his and not mine.
He writes in his JIRA ticket, "regression testing introduced bug/issue, if you're busy, I can fix it." He will break things while I give him the code in working conditions, without consulting or asking me. The issues he introduces get audited before I can see them.
How can I ensure that this senior developer does not continue to break things, which end up becoming my responsibility?