His family and friends acknowledged that Mr. Buckel had become distraught recently over the national politics of climate change — “all that’s going on with the Trump administration and the rollback by Pruitt at the Environmental Protection Agency,” Mr. Kaelber said, referring to agency’s embattled administrator, Scott Pruitt.

In retrospect, Mr. Morales said he knew Mr. Buckel had been upset as recently as February when he began discussing articles about the environment, for instance one about how 96 percent of human beings breathe polluted air and another about the Arctic Circle experiencing record breaking temperatures.

Mr. Morales said two weeks ago Mr. Buckel sent him an email with all his contacts for the compost site, showing him how to complete paperwork, annual reports and other documents that would need to be turned over to city agencies.

With a back injury that limited his work, Mr. Buckel was struggling over what he could do next. Mr. Kaelber said he interpreted this “dramatic act” as “what can a person at age 60 do that people would pay attention to.”

Mr. Buckel started his career as a Legal Aid lawyer, and gained national prominence by arguing cases with Lambda Legal, an organization that fights for the civil rights of lesbian, gay, bisexual and transgender people.

Mr. Buckel was the lead lawyer in the case in which a Nebraska sheriff was found liable for failing to protect a transgender man who was murdered in Falls City, and was the strategist behind same-sex marriage cases in New Jersey and Iowa.