It is difficult and saddening to tell coworkers that a colleague, and possibly a friend, of theirs has died, but, of course, it has to be done. Even an expected death from, say, advanced cancer, may be devastating news. A written memo is a formal, respectful way to inform people of the details of a death, and it gives readers space to react and mourn in the way that feels best to them. Many of the principles and considerations that govern informing someone of a death in person apply to informing them in writing.
Gather the relevant information--primarily when, where and under what circumstances the person died. In some cases, all the details will not be immediately known, or suspected but not yet confirmed (often in the case of an apparent suicide or homicide). Understand what information can and cannot be shared with coworkers.
Begin writing a memo with a short sentence informing the workers that their co-worker has died. Use the full name of the deceased. Elaborate in subsequent sentences. Use formal but not flowery language to refer to the death itself. Refrain from overly-elaborate or possibly offensive euphemisms such as, "Last night, Jane Smith lost her battle with lung cancer, and slipped out of this world." Be straightforward--use "died" or "passed away." Quote a family member, if it's appropriate, e.g., "She died in her home, surrounded by her loved ones."
Suicide is a tragic, delicate matter. Phrase it as the person "took his own life" rather than a less-sensitive phrase, like "killed himself" or "committed suicide."
Trim unnecessary words and information from the memo. Those who read it will likely be in shock over their co-worker's death; they don't need to read a three-paragraph quote from the company president about it. (Keep appropriate quotes to one or two sentences.) Stick to the basics.
If the family has already scheduled a memorial service, include that information at the end of the memo. If not, just include a note to the effect that when the memorial service is announced, everyone will be notified.
Assemble and briefly make it known in the memo that grief resources are available to workers. These resources might include books on processing loss, articles about the stages of mourning and fact sheets listing the symptoms of depression, which grief can trigger.
Clear the memo with the human resources department, if your company has one, before sending it to make sure you have phrased things in an appropriate way and didn't disclose information that should not have been released.
Find out if your company health insurance will cover grief counselling services if an employee needs them. Consider quietly launching--and following through on--a company suicide awareness and prevention campaign. Wait at least a few weeks after the funeral. To announce such a campaign immediately after the person's death could rightfully be construed as insensitive.
Some people may have very strong grief reactions. "Know exactly how to access immediate medical or mental health care," advises a resource guide developed by Mothers Against Drunk Driving (MADD) and reprinted by the National Center for PTSD (Post-Traumatic Stress Disorder).