A memorial to Charlene Holmes, 16, appeared during a vigil, a day after a drive-by shooting took her life and injured Thanialee Cotto, 17.

With nearly a month passed since the shooting death of Charlene Holmes, 16, an hourlong vigil is planned for 7:15 p.m. Friday for “peace in the neighborhoods of Cambridge.”

The vigil meets at Willow and Lincoln streets in the Wellington-Harrington neighborhood — near the Willow Street address where someone in a black sedan sped past between 8 and 8:15 p.m. June 3, firing at a home Charlene and her sister happened to be passing. Holmes, a sophomore at Cambridge Rindge & Latin School, was killed. Thanialee Cotto, a senior at the school, was injured as she sat on the porch, braiding a man’s hair.

There have been four shooting incidents since in Cambridge, although none like the June 3 drive-by. The latest, reported late Sunday, seems to have been a self-inflicted gunshot wound; two others were reports of shots fired with no injuries. But it has been unnerving.

“We are aware there have been multiple incidents of violence in the city,” said Cheryl Maynard, an administrator at First Holiness Church, on Columbia Street in Wellington-Harrington.

Some 20 churches are involved in the vigil, Maynard said, and there will be other events scheduled in other parts of the city.

There has been no arrest in the drive-by, although almost immediately after it happened witnesses and neighbors seemed knowledgeable about what was behind it.

Witnesses said they’d heard the shooting was “calculated” and intended as “retaliation,” with the man getting his hair braided being the target. There were references to “that gang out there” and city councillor Marjorie Decker told the Boston Herald that “in general, it’s a safe neighborhood [where] neighbors have identified one problem area” — with the Herald confirming that Cambridge police had been called to the address of the shooting 29 times since 2005.

Investigators at work

Shortly after the shooting investigators searched the second-floor apartment at that address, according to Middlesex District Attorney spokeswoman Jessica Venezia Pastore, but have not discussed what they found there or made an arrest, saying only “We are encouraged by the leads we have and we have every confidence we will solve this crime.”

At a June 4 vigil on Willow Street, Charlene’s father, aunt and a family friend, Cheryl Hall, pleaded to mourners to talk to police and help arrest a suspect. “If you guys really loved her you would tell the people in the blue what really happened,” Hall was quoted as saying in The Cambridge Chronicle.

One elected city official, in acknowledging the details of the case known to police as the investigation began, called the lack of action “weird.”

“We have three teams of detectives working on this case in coordination with the Massachusetts State Police and Middlesex County District Attorney’s Office. We have a number of solid leads we’re following up on and are comfortable that the investigation is moving along at a decent pace,” Cambridge police spokesman Dan Riviello said. A message seeking an update on the case was also left with the District Attorney’s Office.

There have been more officers in the area since the shooting, Riviello said, as well as throughout the city as the department’s summer deployment plan — which includes bicycle officers — took effect.

One resident found during a recent visit to the neighborhood confirmed the increased police presence and said he expected something would break in the case before school started. The street hosts the King Open School, also the site of the Cambridge Street Upper School as of Sept. 4, and Donnelly Field.

The Friday vigil is described as including “churches, clergy, youth and concerned citizens to pray” for healing, order, prayer and peace and empowerment — forming the acronym Hope.

It is sponsored by Cambridge Churches United. For information, call First Holiness Church at (617) 661-1925 or send e-mail to first_holiness@yahoo.com.

This post was updated June 26, 2012, with information from Cheryl Maynard and June 27, 2012, with information from Dan Riviello.