The man accused of murdering a man who was found bleeding in the Wal-Mart parking lot in Falmouth last week was ordered held without bail Monday during his initial court appearance.

Kenneth Briggs Jr., 27, formerly of Portland but now homeless, said nothing during the brief hearing before Justice Lance Walker at the Cumberland County Courthouse in Portland. He was also ordered to undergo a mental exam.

Briggs was arrested Friday and charged in the Aug. 15 stabbing of Roger Nelsen, 67, who had been living in his car.

Court documents detailing the case against Briggs remained sealed Monday. It is unclear how police tied Briggs to the killing and what motive he may have had.

Nelsen was found lying in a pool of blood by a Falmouth police officer on patrol. Nelsen appeared to have stab wounds and was able to speak with the officer briefly before losing consciousness. He was taken to Maine Medical Center in Portland, where he died on Aug. 17.

Briggs and Nelsen previously lived together, Maine State Police said.

The prosecutor, Assistant Attorney General Megan Elam, said at Monday’s hearing that the state was lifting its request to keep police affidavits impounded. But Briggs’ attorneys, Molly Butler Bailey and Heather Gonzales, asked the judge to keep the records sealed for now.

Briggs was not required to enter a plea to the murder charge because the case against him has yet to be presented to a grand jury.

Briggs also faces a charge of felony theft and Butler Bailey entered a not guilty plea on his behalf in that case. Throughout the hearing, Briggs, wearing a suit and tie, stood between his attorneys and whispered with them occasionally.

In the theft case, Briggs is accused of stealing from Nelsen on April 7. Details of that case were also unavailable Monday. The clerk’s office was still sorting through the case files by the time the courthouse closed to determine which documents in each case remained sealed. More documents may be released Tuesday, but the affidavits in the murder case, which would contain the bulk of the information related to Nelsen’s death, will probably not be available for a month or more.

The prosecutor and defense attorneys requested jointly that Briggs undergo a mental examination to determine whether he is competent to stand trial and whether he has the capacity to be held criminally responsible.

“Our concerns are significant enough that we have requested a psychological evaluation,” Butler Bailey said outside the courtroom after the hearing. She declined to comment further, because she and Gonzales were only assigned to the case Monday and are still reviewing it. Elam also declined to comment.

Both Briggs and Nelsen have prior criminal records in Maine.

Nelsen was required by law to register as a sex offender because of a 2006 conviction in federal court on a child pornography charge. In that case, he was sentenced to serve 33 month in federal prison.

Briggs has a lengthy adult criminal record dating to 2009 on charges including theft, burglary of a motor vehicle, criminal mischief, criminal trespassing, violating the conditions of his release on bail, disorderly conduct, violating protection from harassment orders and terrorizing.

Briggs was sentenced most recently in Belfast Superior Court to serve 60 days in jail for violating a protection from abuse order taken out against him by a woman there.