Cohen's letter said that "Jim Tobin of Senator Cohen’s Bangor office has asked me to look into your concerns about the handling of the investigation of your son’s death. In your behalf, I have written to the Attorney General James Tierney. I will write to you as soon as I have received a response from him. I have also discussed the situation with officials of the Federal Bureau of Investigation. As you are aware, the FBI does not investigate suspected homicides. However, they did make an initial follow up to concerns expressed to them about the possibility of a cover-up of the facts in the case. Their initial work has led them to conclude that there has been no cover-up  and the matter is no longer under consideration. 1 
     "The separation of powers between the branches of government dictates that members of the legislative branch, as in Senator Cohen’s case, cannot interfere with the workings of the judicial, or courts, branch. I am pleased to try to find some information for you, but Senator Cohen cannot legally be involved beyond this effort.
     "Again, I will write to you again as soon as I have more information."
     I never heard from Senator Cohen’s office again. But Senator Cohen became quite involved in the murder of a young man from Bangor, Maine who was murdered in Baltimore, Maryland years later. The separation of powers didn’t hinder him from getting involved in a case that didn’t fall back on the Maine Attorney General’s Office. March 9, 1996—nine years after Cohen’s office wrote me that Senator Cohen cannot interfere with workings of the judicial, or courts—an article in the Baltimore Sun said that
"... Yesterday, two aides from the office of Republican Sen. William S. Cohen of Maine met with Maj. Wendell France, head of Baltimore’s homicide unit. A police spokesman, however, said homicide detectives have reopened the case and found no new evidence. He also said he viewed the visit from senatorial aides as an insult to the department. ‘It’s unfortunate that a family connected with a U.S. senator would resort to that as a way of applying pressure on the department,’ spokesman Sam Ringgold said yesterday.”
1.  In early 1987 when the FBI were investigating the Maine State Police for sexual misconduct and perjury during drug cases, Attorney Marshal Stern told the news media that the cover up should not be allowed to continue. And the news also said the misconduct grew out of the drug case that involved Mike's murder.